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UC Berkeley

UC Berkeley

The University of California, Berkeley (also known as Cal, UCB, UC Berkeley, The University of California, California, or simply Berkeley) is a public coeducational university situated east of the San Francisco Bay in Berkeley, California, overlooking the Golden Gate. The oldest and flagship campus of the University of California system, Berkeley is a leading research university. Its programs, libraries, and faculty are consistently ranked among the best in the world. Founded in 1868, Berkeley enjoyed a golden age in the physical, chemical, and biological sciences in the 20th Century, leading to the development of the first cyclotron by Ernest O. Lawrence, the isolation of the human polio virus, and the discovery of numerous elements, including Plutonium, Berkelium, and Californium. Nobel Prizes have been awarded to nineteen past and present faculty, among the 54 Nobel laureates associated with the university. The campus gained attention worldwide with the birth of the Free Speech Movement and student protests against United States involvement in the Vietnam War, significantly defining the 1960s in America. Later developments include a number of key technologies associated with the development of the Internet, BSD Unix, and the Open Source Software movement.

Academics

Open Source Software movement The University of California, Berkeley currently boasts 221 American Academy of Arts & Sciences Fellows, 3 Fields Medal holders, 83 Fulbright Scholars, 139 Guggenheim Fellows, 11 Howard Hughes Medical Institute Investigators, 28 MacArthur Fellows, 87 members of the National Academy of Engineering, 128 members of the National Academy of Sciences, 8 Nobel Prize winners, 3 Pulitzer Prize winners, 83 Sloan Fellows, and 7 Wolf Prize winners among a bevy of distinguished faculty. According to the National Research Council, Berkeley ranks 1st nationally in the number of graduate programs in the top 10 in their fields (97 percent) and 1st nationally in the number of "distinguished" programs for the scholarship of the faculty (32 programs). Similarly, Berkeley is the only university in the nation to have all of its PhD programs ranked in the top five by US News and World Report. It also ranks in the top three in both of the US News ranked undergraduate programs, Business and Engineering. World Universities Rankings performed in 2004 by the UK Times Higher Education Supplement named Berkeley No. 2 in the world overall. No. 1 Engineering and IT, No. 3 in Humanities & Social Sciences, and No. 4 in science. Similar rankings performed in 2004 by the Institute of Higher Education in Shanghai placed Berkeley at No. 4 among the Top 500 World Universities. Undergraduate rankings performed in 2006 by US News and World Report place Berkeley as the country's top public university but at No. 20 overall in the nation. Berkeley has graduated more students who go on to earn doctorates than any other university in the United States, and its enrollment of National Merit Scholars was third in the nation prior to 2002, when participation in the National Merit program [http://ucnewswire.org/news_viewer.cfm?story_PK=4989& was discontinued]. With more than 7,000 courses in nearly 300 degree programs, the university awards about 5,500 bachelor's degrees, 2,000 master's degrees, 900 doctorates and 200 law degrees each year. The University's library system houses nearly 10 million volumes, spread over 32 departmental (and affiliated) libraries. Its library is ranked third in North America by the Association for Research Libraries after Harvard University and Yale University.

History

Yale University In 1866, the land which is now the Berkeley campus was first purchased by the private College of California (established by Congregational minister Henry Durant in 1855). However, lacking the funds to operate, the College of California merged with state-run Agricultural, Mining, and Mechanical Arts College, forming the University of California on March 23, 1868, with Durant becoming the first president. The university first opened in Oakland in 1869. In 1873, with the completion of North and South Halls, the university relocated to the Berkeley campus with 167 men and 222 women students enrolled. (Note that Berkeley is not the oldest public university in California; that honor belongs to San Jose State University.) Through the middle decades of the 20th century, the Berkeley campus enjoyed a golden age in the physical, chemical and biological sciences. During that period, with Professor Ernest O. Lawrence's invention of the cyclotron, researchers affiliated with the campus discovered a great number of chemical elements heavier than uranium, the only ones known at that time, garnering a number of Nobel Prizes for these efforts along the way. Two of the elements, Berkelium and Californium, were named in honor of the university. Another two, Lawrencium and Seaborgium, were named in honor of faculty members Ernest O. Lawrence and Glenn T. Seaborg. During World War II, Lawrence's Radiation Laboratory in the hills above Berkeley began to contract with the U.S. Army in efforts to help understand the fundamental science needed to develop the atomic bomb (including the then-secret discovery of plutonium by Seaborg). Physics professor J. Robert Oppenheimer was named scientific head of the Manhattan Project in 1942. The University agreed to manage the project without knowing its purpose the same year, beginning a relationship with the Department of Defense which has endured to the present. Room 307 of Gilman Hall, where Seaborg discovered plutonium, is now a National Historic Landmark. Two other University of California managed labs, Lawrence Livermore National Laboratory and Los Alamos National Laboratory, were established during this time period. During the McCarthy era in 1949, the Board of Regents adopted an anti-communist loyalty oath to be signed by all University of California employees. A number of faculty members firmly took a stand against the oath requirement and were eventually dismissed. They were reinstated with full honor and back-pay ten years later; one of them, Edward C. Tolman — the noted comparative psychologist — now has a building on the campus named after him (it houses the departments of psychology and education). An oath to "support and defend the Constitution of the United States and the Constitution of the State of California against all enemies, foreign and domestic" is still required by all UC employees. In 1952 the University of California became an entity separate from the Berkeley campus as part of a major restructuring of the UC system, and each campus was given its own Chancellor, and greater autonomy. 1962 ushered in a new day for people with disabilities when Ed Roberts became a student. He would found the Independent Living movement with other wheelchair users while on campus. The University gained notoriety worldwide nearly a century after its founding for the student body's active protests against United States involvement in the Vietnam War. This period of social unrest on campus could be traced to the Free Speech Movement, which originated on the Berkeley campus in 1964 and inspired the political and moral outlook of a generation. Today, the majority of students at UC Berkeley are less politically active than their predecessors and have political opinions similar to students at most other American universities. However, a small number of outspoken radical groups continue to flourish and thrive.

Reputation

In addition to UC Berkeley’s reputation as one of the best research universities in the world, it also has a reputation for student activism. Although there are claims that the university’s students have become politically apathetic and civically disengaged in the decades since the Free Speech Movement and Vietnam War, there are also counter-claims that today’s campus activism spans a broader range of causes (making it appear more dispersed) and utilizes new approaches, such as e-mail networks and listservs. Beginning in 1996, California Proposition 209, which ended Affirmative Action in California and the University of California system, and its subsequent impact on the campus population of African American, Latino, and Native American students helped to rekindle activism around issues of race. In this instance, reaction came not only from students, but also from alumni. Four alums established the IDEAL Scholars Fund to increase the number of qualified, underrepresented students of color at UC Berkeley. Other creative protests included those in support of Professor Ignacio Chapela in his campaign for "tenure justice” against claims of undue influence from Novartis and the biotechnology industry. Chapela was eventually granted tenure.

Campus architecture and architects

Novartis The campus is 1,232 acres (5 km²) in its entirety, though the main campus is on the western 178 acres (0.7 km²). Despite its urban setting, the campus manages to maintain a surprisingly park-like atmosphere, crossed by two creeks and including the tallest stand of hardwood trees in North America. Overlooking the main campus on the east side are several research units, most notably the Lawrence Berkeley National Laboratory, the Space Sciences Laboratory, the Mathematical Sciences Research Institute, and the Lawrence Hall of Science. Much of the rugged upper hill territory is still undeveloped. Residential Halls and administrative buildings spill out into the city of Berkeley, particularly to the south of the campus. The campus and its surrounding community are home to a number of notable buildings by early 20th century campus architect John Galen Howard, his peer Bernard Maybeck (best known for the Palace of Fine Arts), and Maybeck's student, Julia Morgan. Later buildings were designed by prominent architects such as Charles Willard Moore (Haas School of Business) and Joseph Esherick (Wurster Hall). Very little of the early University of California (c. 1868–1903) remains, with the Victorian Second Empire style South Hall (1873) and Piedmont Avenue (designed by Frederick Law Olmsted) being notable exceptions. What is considered the historic campus today was the eventual result of the 1898 "International Competition for the Phoebe Hearst Architectural Plan for the University of California," funded by the mother of William Randolph Hearst and initially held in the Belgian city of Antwerp (eleven finalists were judged again in San Francisco, 1899). This unprecedented competition came about from one-upmanship between the prominent Hearst and Stanford families of the Bay Area. In response to the founding of Stanford University, the Hearst Family decided to "adopt" the fledgling University of California and develop their own world-class institution. Although a Frenchman, Emile Bénard, won the competition, he disliked the "uncultured" San Francisco atmosphere and refused to revise and oversee the plan. He was replaced by the fourth place winner John Galen Howard, who would later become UC Berkeley's resident campus architect. Only University House, designed by architect Albert Pissis and then home to the President of the University of California, was placed according to the Bénard plan (it is today the home of UC Berkeley's Chancellor). Albert Pissis]] Much of the older campus is built in the stately Beaux-Arts Classical style, which was regarded as the most cultured, beautiful, and "scientific" style by the cultural establishment at the time of the competition, and thus was the style preferred by John Galen Howard and Phoebe Hearst (who paid his salary). With the support of University President Benjamin Ide Wheeler, Howard designed over twenty buildings, which set the tone for campus up until it post-World War II expansion in the 1950s and 60s. These included the Hearst Greek Theatre, the Hearst Memorial Mining Building, Doe Memorial Library, California Hall, Wheeler Hall, (Old) Le Conte Hall, Gilman Hall, Haviland Hall, Wellman Hall, Sather Gate, and the 307-foot Sather Tower (nicknamed "the Campanile" after St. Mark's Campanile in Venice). Buildings he regarded as temporary, non-academic, or not particularly "serious" were designed in shingle or Collegiate Gothic styles, such as North Gate Hall, Dwinelle Annex, and Stephens Hall. This collection of buildings (Founders' Rock, University House, Faculty Club and Glade, Hearst Greek Theatre, Hearst Memorial Mining Building, Doe Library, Sather Tower and Esplanade, Sather Gate and Bridge, Hearst Gymnasium, California, Durant, Wellman, Hilgard, Giannini, Wheeler, North Gate and South Halls), collectively are a California Historical Landmark and are listed in the National Register of Historic Places. Bowles Hall—built in 1928—is California's oldest state-owned dormitory and is also listed in the National Register of Historic Places. John Galen Howard retired in 1924, his support base gone with both Phoebe Hearst's death and President Wheeler's resignation in 1919. William Randolph Hearst, seeking to memorialize his mother, contributed to Howard's resignation by commissioning Bernard Maybeck and Julia Morgan to design a series of dramatic buildings on the southern part of the campus. These were originally to include a huge domed auditorium, a museum, an art school, and a women's gymnasium, all arranged on an eastward esplanade and classically oriented towards the campanile. However, only the Hearst Women's Gymnasium was completed before the Great Depression, at which point Hearst decided to focus on his estate at San Simeon instead. San Simeon The dramatic increase in enrollment during the 1950s, 1960s, and 1970s led to the rapid expansion of the campus, beginning with the University's appropriation of the north end of Telegraph Avenue to form Sproul Plaza and headed on its east side by Sproul Hall, a new neoclassical building for the campus administration. However, the administration moved out of Sproul and into California Hall, situated in the heart of campus, after students barricaded themselves in Sproul during the 1964 Free Speech Movement. (Today, Sproul Hall houses Student Services and the Admissions Office, and Sproul Plaza is the center of student activities.) A series of huge Brutalist concrete buildings were also built to provide much-needed housing, lab, office, and classroom space, including Evans Hall, Cory Hall, Wurster Hall, Davis Hall, McCone Hall, Zellerbach Hall, the undergraduate dorms Units 1, 2, and 3, and others. Gray-green Evans Hall is the tallest instructional building on the campus and houses the offices of faculty in mathematics, statistics, and economics, which once included former Assistant Professor of Mathematics Ted Kaczynski, infamously known as the Unabomber. Students widely revile Evans as the ugliest building on campus, with the possible exception of Wurster Hall. (Ironically, Wurster Hall is the building that houses UC Berkeley's architecture department.) The most recent campus development plan lists Evans Hall as a candidate for demolition within the next fifteen years. Cory Hall, the electrical engineering building, was the site of two attacks by the Unabomber in 1982 and 1985. Its neighbor Soda Hall (computer science) is one of the few classroom buildings on campus with showers. It was completed in August 1994, at the cost of $35.5 million, raised entirely from private gifts. Dwinelle Hall is another large building on campus; its rooms are strangely numbered both because Dwinelle Hall was built on a slope, with entrances on different levels, and because expansion wings were numbered differently from the original building. Because this confusing building is host to both large lower-division lecture classes and many smaller discussion classes, it is sometimes called the "freshman maze." Underneath UC Berkeley's oldest buildings is a system of steam tunnels which carry steam to those buildings for heat and power. During the 1960s, Berkeley students chained the doorknobs of the Chancellor's office in protest over the Vietnam War. The Chancellor, having no other way in or out of the building, used the steam tunnels to escape. Afterwards, the exterior double doors on that building were changed so they only had one doorknob, and this remains today. Recent developments include the newly completed Jean Hargrove Music Library, only the fourth free-standing music library to be constructed in the United States. Current major construction projects include the first free-standing buildings to be devoted to East Asian Studies in the United States, the C.V. Starr East Asian Library and the Chang-Lin Tien Center for East Asian Studies, designed by noted architects Tod Williams and Billie Tsien; the former has broken ground and is scheduled for completion in Fall 2007. The headquarters building for [http://www.citris-uc.org/ CITRIS] (Center for Information Technology Research in the Interest of Society) broke ground in 2004 and is expected to be completed in 2007; it will include nanofabrication facilities, labs, and classrooms. Finally, the massive 285,000 square foot Stanley Biosciences and Bioengineering Facility will be completed in mid-2006; oriented towards health-related interdisciplinary research, three-quarters of the building is devoted to labs and specialized facilities while one-quarter will be office and instructional facilities.

Organization

Chancellors

The position of Chancellor was created in 1952 during the reorganization and expansion of the University of California; there have since been nine inaugurated chancellors (1 was acting chancellor): # Clark Kerr (1952–1958) # Glenn T. Seaborg (1958–1961) # Edward W. Strong (1961–1965) # Martin E. Meyerson (1965, acting) # Roger W. Heyns (1965–1971) # Albert H. Bowker (1971–1980) # Ira Michael Heyman (1980–1990) # Chang-Lin Tien (1990–1997) # Robert M. Berdahl (1997–2004) # Robert J. Birgeneau (2004–present)

Colleges and schools

Robert J. Birgeneau Berkeley's 130-plus academic departments and programs are organized into 14 colleges and schools. ("Colleges" are both undergraduate and graduate, while "Schools" are graduate-only, the exception being the School of Business.):
- Haas School of Business
- College of Chemistry
- Graduate School of Education
- College of Engineering
- College of Environmental Design
- Graduate School of Journalism
- Boalt Hall School of Law
- School of Information
- College of Letters and Science
- College of Natural Resources
- School of Optometry
- School of Public Health
- Richard & Rhoda Goldman School of Public Policy
- School of Social Welfare

Contributions to computer science

Cal has nurtured a number of key technologies associated with the early development of the Internet and the Open Source Software movement. The original Berkeley Software Distribution, commonly known as BSD Unix, was assembled in 1977 by Bill Joy as a graduate student in the computer science department. Bill Joy also developed the original version of vi. PostgreSQL emerged from faculty research begun in the late 1970s. Sendmail was developed at Berkeley in 1981. BIND (Berkeley Internet Name Domain package) was written by a team of graduate students around the same time period. The Tcl programming language and the Tk GUI toolkit were developed by faculty member John Ousterhout in 1988. SPICE and espresso, popular tools for IC Designers, were also invented at Berkeley under the direction of Professor Donald Pederson. The RAID and RISC technologies were both developed at Berkeley under David Patterson. Perhaps the most pervasive contribution to computing from UCB has been the algorithms and analysis of floating-point arithmetic, led by Professor William Kahan. These include extensive and ongoing contributions to the IEEE 754 standard. The XCF, an undergraduate research group now located in Soda Hall, has been responsible for a number of notable software projects, including GTK+, The GIMP, and the initial diagnosis of the Morris worm. In 1992, Pei-Yuan Wei, an undergraduate at the XCF, created ViolaWWW, one of the first graphically-based web browsers. ViolaWWW was the first browser to have embedded scriptable objects, stylesheets, and tables. In the spirit of Open Source, he merely donated the code to Sun Microsystems, thus inspiring Java applets. ViolaWWW would also inspire researchers at the National Center for Supercomputing Applications to create the Mosaic web browser. SETI@home was one of the first widely disseminated distributed computing projects, allowing hobbyists and enthusiasts to participate in scientific research by donating unused computer processor cycles in the form of a screen saver. In an interesting example of the confluence of intellectual ideas, many of the arguments for the efficacy of Open Source software development, and of the Wikipedia project itself, find parallels in writings on urban planning and architecture published in the late 1970s by Christopher Alexander, a Berkeley professor of architecture. Across campus around that same time period, John Searle, a Berkeley professor of philosophy, introduced a celebrated critique of artificial intelligence using the metaphor of a Chinese Room. List of research projects conducted at Berkeley:
- Daedalus project - Combine intelligent adaptive applications with smart networking software that can multiplex connections over a wide variety of different networking technologies.
- Digital library project
- GiST - A Generalized Search Tree for Secondary Storage
- Harmonia research project - open interactive programming tools
- Sather - Object oriented language derived from Eiffel programming language
- Not Another Completely Heuristic Operating System - Instructional software for teaching undergraduate, and potentially graduate, level operating systems courses.

Sports and traditions

Not Another Completely Heuristic Operating System Not Another Completely Heuristic Operating System Cal's sports teams compete as the California Golden Bears. They participate in the NCAA's Division I-A, and in the Pacific Ten Conference. The annual football Big Game between the Bears and their rivals the Stanford Cardinal is the most important game on Cal's schedule. The winner of this game gains custody of the Axe. The Play, one of the most dramatic last-minute plays in college football history, occurred on November 20, 1982, in the 85th Big Game. Berkeley's current football coach, Jeff Tedford, has led the team to some of the most successful campaigns in the school's history. Indeed, seen on campus, variously, have been shirts saying "Ted Heads," "Tedford for President," and "Tedford is God." Berkeley's main athletic venues, Memorial Stadium and Haas Pavilion, rank as some of the best college sports facilities in the nation. The Stadium, built to model the Colosseum in Rome, is consistently ranked as one of the best views by Sports Illustrated. Across the street is Witter Rugby Field, home to Cal's varsity rugby team, the oldest varsity team on campus (they were founded in 1886). The Bears, coached by alumnus and campus legend Jack Clark, are utterly dominant on the American university rugby scene, once winning 12 consecutive national titles. Overall, the Bears have won the national championship 21 times since it was first awarded in 1980, and won the national championship in 2005. In basketball, Haas Pavilion, donated in part by the owners of Levi-Straus and built on top of the old Harmon Gymnasium, is considered one of the most intimidating environments for visiting teams. Haas Pavilion Close to Haas Pavilion is Edwards stadium. This is where the Cal track team practices and competes. The University of California Marching Band has served the university since 1891, and performs at every football game and many other sports games and spirit activities. The university also has a Rally Committee, formed in 1901, the members of which have served as the official guardians of Cal Spirit ever since. RallyComm wears traditional blue and gold rugbies. The official school colors, Yale Blue and California Gold, were established in 1874. Yale Blue was chosen because most of the original faculty were Yale University graduates. Gold was selected to represent the Golden State of California. The official mascot is Oski the Bear, who first debuted in 1941. Previously, live bear cubs were used as mascots at Memorial Stadium. It was decided in 1940 that a costumed mascot would be a better alternative to a live bear. Named after the Oski-wow-wow yell, he is cared for by the Oski Committee. The wearer of the costume is kept a secret. It is the tradition to have the basketball player with the largest feet donate his shoes for Oski to wear. Cal's independent student-run newspaper is the Daily Californian. Founded in 1871, The Daily Cal became independent in 1971 after the campus administration fired three senior editors for encouraging readers to take back People's Park. Cal's student-run radio station, KALX-FM, broadcasts on 90.7 MHz.People's Park The annual summer orientation for incoming freshmen is called CalSO, short for Cal Student Orientation. The Associated Students of the University of California (ASUC) is the student government organization that controls funding for student groups and organizes on-campus student events. It is currently the only autonomous student government in any public U.S. university.

Lists of distinguished Berkeley people


- List of Nobel laureates associated with UC Berkeley
- List of UC Berkeley faculty
- List of UC Berkeley alumni

Research facilities


- Lawrence Berkeley National Laboratory
- Helen Wills Neuroscience Institute
- Renewable and Appropriate Energy Laboratory

Points of interest


- University of California Botanical Garden
- Hearst Greek Theatre

Further reading


- Susan Dinkelspiel Cerny, Berkeley Landmarks. An Illustrated Guide to Berkeley, California's Architectural Heritage. Berkeley Architectural Heritage Association, 2001, ISBN 0-970-667604
- Jo Freeman, At Berkeley in the Sixties: The Education of an Activist, 1961-1965. Indiana University Press, 2003, ISBN 0-253-216222
- Harvey Helfand, University of California, Berkeley. Princeton Architectural Press, 2001, ISBN 1-568-982933
- W. J. Rorabaugh, Berkeley at War: The 1960s. Oxford University Press, 1990, ISBN 0-195-066677
- Geoffrey Wong, A Golden State of Mind. Trafford Publishing, ISBN 1-552-126358

External links

Official websites


- [http://www.berkeley.edu/ Main Berkeley website]
- [http://newscenter.berkeley.edu/ Berkeley NewsCenter]
- [http://www.berkeley.edu/news/in_news/ Berkeley in the News]
- [http://www.dailycal.org/ The Daily Californian—independent student newspaper]
- [http://www.berkeley.edu/news/berkeleyan/ The Berkeleyan—faculty and staff newsletter]
- [http://calbears.ocsn.com/ Official athletic site]
- [http://calband.berkeley.edu/ The University of California Marching Band official web site]
- [http://ucrc.berkeley.edu/ The University of California Rally Committee official web site]
- [http://www.asuc.org/ ASUC student government site]
- [http://www.berkeley.edu/news/berkeleyan/2004/12/01_rankings.shtml "We're No. 2! Now What?"— Berkeleyan article about Berkeley's rankings and their validity]
- [http://www.csua.berkeley.edu CSUA (Computer Science Undergraduate Association) web site]
- [https://cal.berkeley.edu @cal, great minds online--UC Berkeley's online alumni community.]

Other


- [http://gocyberbears.com/ Go Cyber Bears - Cal's Insider Look at Athletics - Sports Fan Webpage]
- [http://calstuff.blogsome.com/ Calstuff: A Student-Run News Blog]
- [http://www.ocf.berkeley.edu/~atwu/firstcultural/berkeleyguide.html A. Twu's Tour of UC Berkeley]
- [http://www.intemperance.net/berkeley/ Loafer's guide to the UC Berkeley campus by Carolyn Dougherty]
- [http://sunsite.berkeley.edu/uchistory/archives_exhibits/online_exhibits/romapacifica/index.html Online Exhibit on the Hearst Architectural Competition]
- [http://terraserver-usa.com/image.aspx?T=4&S=10&Z=10&X=2826&Y=20959&W=3 TerraServer-USA aerial image of campus]
- [http://www.calpatriot.org/ The California Patriot: Berkeley's Conservative Student Voice]
- [http://www.caldems.com/ The Cal Berkeley Democrats]
- [http://www.ocf.berkeley.edu/~bpreview/ The Berkeley Political Review - A non-partisan political quarterly]
- [http://www.arl.org/ Association for Research Libraries]
- Category:University of California California Category:Association of American Universities Category:California Historical Landmarks Category:National Register of Historic Places ja:カリフォルニア大学バークレー校

Public university

is a public university. ]] .]] & Cambridge.]] A public university is an institution of university higher education that is predominantly funded by public means through a national or regional government. In places such as Australia, Canada, Germany, Portugal, South Africa, the United Kingdom and other countries in Europe, most significant universities are public, while in the United States and Japan, both public and private universities are common and generally regarded as having the same standards. Many major public universities around the world were formerly private or religious institutions. Public university tuition, if any, is typically lower than in private universities. In the United States, most public universities are state universities, which are founded and operated by state government entities. Every U.S. state has at least one public university to its name, and the largest states have more than a dozen. States generally charge higher tuition to out-of-state students, a practice which the United States Supreme Court has deemed constitutional because the state is acting as a market participant providing a service, rather than protecting a fundamental right. It has never been determined whether the U.S. Constitution would allow the federal government to establish a federal university system, but the only federally chartered universities that currently exist are those under the auspices of the U.S. military, such as West Point, the Naval Academy and the United States Air Force Academy. In Canada and Germany, education, including the administration of universities, is the responsibility of the individual provinces (in Canada) or Bundesländer (in Germany). In Taiwan, public ("national") universities are considered to be generally more prestigious than private universities and require higher entrance examination scores. In mainland China today, few private universities exist, and have only appeared in recent years. Several have been founded by large (public) institutions as legally independent spin-offs. Most are, relatively, not highly regarded, being seen by many as focused primarily on income generation rather than the educational endeavor. While historically in the United States, the bulk of the highest-ranked institutions have been private, public institutions like the University of Michigan, the University of California at Berkeley and Los Angeles, and the University of Virginia have also proven to be some of the most prestigious in the country. World-wide, public institutions like Beijing University, ETH Zurich, Oxford, Cambridge, and Tokyo University are also held in simlar esteem. In fact, in a recent worldwide university study done by the London Times Educational Supplement, four of the top 10 universities were public, with UC Berkeley 2nd, Cambridge and Oxford 5th and 6th, and ETH Zurich rounding out the top 10. World rankings by Shanghai Jiaotong University came up with similar findings. Category:Academia Category:Colleges and universities

San Francisco Bay

The San Francisco Bay is a shallow, productive estuary in which water draining approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean. Technically, the Sacramento River flows into Suisun Bay, which flows through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay, although the entire group of interconnected bays are often referred to as "the San Francisco Bay." San Francisco Bay is located in the US state of California, surrounded by a contiguous region known as the San Francisco Bay Area, dominated by the big cities San Francisco, Oakland, and San Jose.

Size

The Bay covers somewhere between 400[http://www.sfmuseum.org/hist9/mcgloin.html] and 1600[http://response.restoration.noaa.gov/cpr/watershed/sanfrancisco/sfb_html/sfbenv.html] square miles (1040 to 4160 square kilometres), depending on which sub-bays (such as San Pablo Bay), estuaries, wetlands, and so on are included in the measurement. The main part of the Bay measures 3 to 12 miles (5 to 20 km) wide east-to-west and somewhere between 48 mi (77 km)1 and 60 mi (97 km)2 north-to-south. One difficulty in obtaining accurate measurements is that the wetlands and inlets of the bay have been gradually and deliberately filled in, changing the Bay's size since the mid-1800s by as much as one third or even more. Recently, large areas of wetlands have been restored, further confusing the issue of the Bay's size. Despite its value as a waterway and harbor, the many thousands of acres (several km²) of marshy wetlands forming the edges of the bay were considered for many years to be wasted space. As a result, soil excavated for building projects or dredged from channels was often dumped onto the wetlands and into other parts of the bay as landfill. From the mid-1800s through the late 1900s, more than a third of the original bay was filled and often built on. The deep, damp soil in these areas is subject to liquefaction during earthquakes, and most of the major damage close to the Bay in the Loma Prieta earthquake of 1989 occurred to structures on these areas. In the 1990s, the San Francisco International Airport proposed filling in hundreds more acres (km²) to extend its overcrowded international runways in exchange for purchasing other parts of the bay and converting them back to wetlands. The idea was, and remains, controversial.

Role in California settlement

The first recorded European discovery of the San Francisco Bay was on November 4, 1769 when Spanish explorer Gaspar de Portolà, unable to find the port of Monterey, California, moored his ship close to what is now Pacifica. Short on water and food, Portolà and an expeditionary crew of 63 men and 200 horses began an overland journey that took them to the summit of the 1200 ft. high Sweeney Ridge, where he sighted the San Francisco Bay. Sweeney Ridge is located in northern San Mateo County, California and is now a part of the Golden Gate National Recreation Area where a monument marks the discovery site. The site is listed on the National Register of Historic Places (NPS-68000022) as No. 394: Site of the Discovery of San Francisco Bay. The first European to enter the bay is believed to have been the Spanish explorer Juan de Ayala, who passed through the Golden Gate on August 5, 1775 in his ship the San Carlos, and moored in a bay of Angel Island now known as Ayala Cove. This famous bay was the epicenter of American settlement in the Far West during the 19th century. From the 1820s onward, American presidents and expansionists coveted the bay as a great natural harbor in the Pacific. After many failed efforts to buy the bay and varying areas around it, the US Navy and Army seized the region from Mexico during the Mexican-American War (1845-1848). On February 2, 1848 California seceded from Mexico with the signing of the Guadalupe-Hidalgo treaty. A year and a half after gaining independence, California requested to join the United_States on December 3, 1849 and was accepted as the 31st State of the union on September 9, 1850. During the California gold rush of 1848-1850s, San Francisco Bay instantly became one of the world's greatest seaports, dominating shipping and transportation in the American West until the last years of the nineteenth century. The bay's regional importance became paramount when in 1869 the transcontinental railroad located its western terminus in Oakland. San Francisco Bay continues to support some of the densest industrial production and urban settlement in the United States. The San Francisco Bay Area is the American West's second-largest urban area with approximately 8 million residents. transcontinental railroad

Ecology

Despite its urban and industrial character, San Francisco Bay and the Sacramento-San Joaquin Delta remain perhaps California's most important ecological habitats. California's Dungeness crab, Pacific halibut, and Pacific salmon fisheries rely on the bay as a nursery. The few remaining salt marshes now represent most of California's remaining salt marsh, supporting a number of endangered species and providing key ecosystem services such as filtering pollutants and sediments from the rivers. Most famously, the bay is a key link in the Pacific Flyway. Millions of waterfowl annually use the bay shallows as a refuge. SF Bay provided the nation's first wildlife refuge, Oakland's artificial Lake Merritt (constructed in the 1860s) and America's first urban National Wildlife Refuge, the San Francisco Bay National Wildlife Refuge (1972). There has been believed to be a sea serpent like monster living in the bay. bay Tellingly, much of the SFBNWR consists of salt evaporation ponds purchased or leased from Leslie Salt Company and its successor, Cargill Corporation. These salt ponds produce salt for a variety of industrial purposes, including chlorine bleach and plastics manufacture, as well as supporting dense populations of brine shrimp, and therefore serving as feeding areas for waterfowl. In 2003, California and Cargill entered one of the largest private land purchases in American history, with the state and federal governments paying about $200 million for 16,000 acres (65 km²) of salt ponds in the south bay. SFBNWR and state biologists hope to restore some of the recently purchased ponds as tidal wetlands.

Miscellaneous

San Francisco Bay is spanned by seven bridges: the Golden Gate Bridge (which was the largest single span suspension bridge ever built at the time of its construction), the Richmond-San Rafael Bridge, the San Francisco-Oakland Bay Bridge, the Hayward-San Mateo Bridge and the Dumbarton Bridge. Two smaller bridges, the Carquinez Strait Bridge and the Benicia Bridge, span the nothern section of the bay. There are four large islands in San Francisco Bay. Isolated in the center of the Bay is Alcatraz, the site of the famous and allegedly escape-proof federal penitentiary. Mountainous Yerba Buena Island is pierced by tunnels linking the east and west spans of the San Francisco-Oakland Bay Bridge. Attached to the north is the artificial and flat Treasure Island, site of the 1939 World's Fair. Closest to shore, Angel Island was known as "Ellis Island West" because it served as the entry point for immigrants from East Asia. (Raccoon Strait, between Tiburon and Angel Island, is the deepest part of the Bay.) The southern part of the Bay, around the city of San Jose, is known as Silicon Valley for its high concentration of high-tech, semiconductor and computer-related industry. The San Francisco Bay is a mecca for sailors, due to consistent strong winds (Beaufort force 6 is common on summer afternoons) and protection from large open ocean swells. Yachting and yacht racing are popular pastimes and the San Francisco Bay area is home to many of the world's top sailors.

See also


- Islands of San Francisco Bay
- List of airports in the San Francisco Bay area

References


- 1. 1999 Grolier Multimedia Encyclopedia.
- 2. 1988 Encyclopedia Britannica.

External links


- [http://www.baycrossings.com/Archives/2001/07_August/barging_in.htm Barging In - A Short History of Liveaboards on the Bay]
- [http://www.spn.usace.army.mil/bmvc/ Army Corps of Engineers Bay Model: Working scale model of the Bay] Category:Estuaries Category:Geography of California Category:San Francisco Bay Area ja:サンフランシスコ湾

Golden Gate

This article is about the strait in California. For other uses see Golden Gate (disambiguation).
Golden Gate (disambiguation)
Golden Gate (disambiguation)
This image is from the [http://gimp-savvy.com/cgi-bin/img.cgi?ails0bcf1nuTSFM1111 GIMP photo archive].
The Golden Gate is the strait connecting the San Francisco Bay to the Pacific Ocean. Since the 1930s it has been spanned by the Golden Gate Bridge. Great tidal flows added with the combined flows of the Sacramento River and the San Joaquin River have scoured a channel several hundred feet deep through the strait. Before the arrival of Europeans in the 18th century, the area around the strait and the bay was inhabited by the Ohlone people. The strait was surprisingly elusive for early European explorers, presumably due to its persistent summer fog. The strait is not recorded in the voyages of Juan Rodriguez Cabrillo nor Francis Drake, both of whom may have explored the nearby coast in the 16th century in search of the Northwest Passage. The strait is also unrecorded in observation by several Spanish galleons returning from the Philippines that laid up in nearby Drakes Bay. The first recorded observation of the strait was nearly two hundred years later in 1769, by Sgt. Jose Ortega, the leader of a scouting party sent north along the peninsula of present-day San Francisco. Ortego reported that he could proceed no further because of the strait. On 5th August 1775 Juan de Ayala and the crew of his his ship the San Carlos became the first Europeans known to have passed through the strait, anchoring in a bay of California which is now named in Ayala's honour. Until the 1840s the strait was called the "Boca del Puerto de San Francisco" (Entrance to the Port of San Francisco). Sometime in the 1840s, before the discovery of gold in California, the entrance acquired a new name. In his memoirs, John C. Frémont wrote, "To this Gate I gave the name of Chrysopylae, or GOLDEN GATE; for the same reasons that the harbor of Byzantium was called Chrysoceras, or GOLDEN HORN." During the summer, the heat in the California Central Valley causes the air there to rise. This can create strong winds which pull cool moist air in from over the ocean through the break in the hills caused by the Golden Gate, commonly causing a stream of dense fog to enter the bay. The strait is located at .

External links


- [http://www.nps.gov/prsf/history/hrs/elpresid/elpresid.pdf National Park Service: Discovery of the Golden Gate]
- [http://CPRR.org/Museum/Golden_Gate_c1895.html Digitally Restored Panoramic Composited View of The Golden Gate, Fort Point, and San Francisco Bay as seen from "Land's End" near Sutro Heights, c. 1895.] Category:Geography of California Category:Straits

Cyclotron

A cyclotron accelerates charged particles with a high-frequency, alternating voltage (potential difference). A perpendicular magnetic field causes the particles to go almost in a circle. The beam spirals out to the edge of the container, as the particles' speeds increase. At this point, the particles' speed approaches the speed of light. The cyclotron was invented by Ernest Lawrence of the University of California, in 1929. He used it in experiments that required particles with energy of up to 1 MeV. Cyclotrons are used today to treat cancer. The bright, adjustable-frequency x-rays produced by a cyclotron's radiation can be adjusted to penetrate limited distances into the human body, in order to kill tumor cells.

How the cyclotron works

The electrodes shown at the right would be in the vacuum chamber, which is flat, in a narrow gap between the two poles of a large magnet. In the cyclotron, a high-frequency alternating voltage applied across the "D" electrodes alternately attracts and repels charged particles. So, the particles accelerate only when passing through the gap between the electrodes. The perpendicular magnetic field (going "down" through the top of the "D" electrodes) forces the particles to travel in a circular path through the D-shaped chambers in the electrodes. The particles move in a circle, because a current of electrons or ions, flowing perpendicular to a magnetic field, experiences a perpendicular force. The charged particles move freely in a vacuum, so the particles follow a circular path. If the particles slow down (lose energy) they will spiral inward. If the device applies energy to the particles, they will speed up, and spiral outward. The serpentine pipes in the electrodes carry cooling liquid to remove the heat that is caused when stray particles hit the electrodes.

Problems solved by the cyclotron

The cyclotron is an improvement of the linear accelerator. A linear accelerator accelerates particles in a straight line, through evacuated tubes. A series of cylindrical electrodes in the tubes switch from positive to negative voltage. In the 1920's, it was not possible to get high frequency radio waves at high power, so the stages of acceleration had to be far apart, to accommodate the low frequency, or more stages were required to compensate for the low power at each stage. Faster particles required longer accelerators than scientists could afford. Later linear accelerators could use high power Klystrons and other devices imparting much more power at higher frequencies, but before these devices existed, the cyclotron was cheaper. Cyclotrons accelerate particles in a circular path. Therefore, a compact accelerator can contain much more distance than a linear accelerator, with more opportunities to accelerate the particles.

Advantages of the Cyclotron


- Cyclotrons have a single electrical driver, which saves both money and power, since more expense may be allocated to increasing efficiency.
- Cyclotrons produce a continuous stream of particle pulses at the target, so the average power is relatively high.
- The compactness of the device reduces other costs, such as its foundations, radiation shielding, and the enclosing building.

Limitations of the cyclotron

The cyclotron has its own limitations. As the beam speed increases, cyclotron radiation is emitted from the side of the beam, because the magnet is turning and slowing, ("braking") the beam. Small cyclotrons with fast beams can waste all of their energy generating radiation at higher beam speeds. In research cyclotrons that accelerated particle beams, the electrical driver was usually sized and powered so that most of its energy was dissipated by generating radiation, with relatively few, very high energy particles. As a result, the cyclotron is usually shielded, so that the operators are not harmed by the x-rays it emits. Most modern cyclotrons are constructed especially to produce bremsstrahlung radiation. Cyclotrons produce spectrally-pure, very-bright far-ultraviolet(λ=less than 400nm), and soft, low-frequency x-rays, that are difficult to produce by other methods. While a significant technical achievement at the time, cyclotrons are too expensive at higher powers. Their limitations caused the invention of the synchrocyclotron (to overcome relativistic effects), and finally the synchrotron, which overcomes the cyclotron's limitations: The electromagnet saturates, and larger cyclotrons are much too large because of the shape of their vacuum chambers. Large linear accelerators do not have bremsstrahlung radiation, because the beam does not change direction. The largest modern linear accelerator is the Stanford Linear Accelerator (SLAC), about two miles (3.2 km) long. It is far more powerful than the largest cyclotron. This is due not only to its length, and straightness, but also to the use of modern high-power and high-frequency klystron microwave power tubes.

Mathematics of the cyclotron

The centripetal force is provided by the transverse magnetic field B, and the force on a particle travelling in a magnetic field (which causes it to curve) is equal to Bqv. So, :\frac = Bqv (Where m is the mass of the particle, q is its charge, v is its velocity and r is the radius of its path.) Therefore, :\frac = \frac v/r is equal to angular speed, ω, so :\omega = \frac And, the frequency :f = \frac Therefore, :f = \frac This shows that for a particle of constant mass, the frequency does not depend upon the radius of the particle's orbit. As the beam spirals out, its frequency does not decrease, and it must continue to accelerate, as it is travelling more distance in the same time. As particles approach the speed of light, they acquire additional mass, requiring modifications to the frequency, or the magnetic field during the acceleration. This is accomplished in the synchrocyclotron. The relativistic cyclotron frequency is f=f_c\frac, where f_c is the classical frequency, given above, of a charged particle with kinetic energy T and rest mass m_0 circling in a magnetic field. The rest mass of an electron is 511 KeV, so the frequency correction is 1% for a magnetic vacuum tube with a 5.11 KV direct current accelerating voltage. The proton mass is nearly two thousand times the electron mass, so the 1% correction energy is about 9 MeV, which is sufficient to induce nuclear reactions. An alternative to the synchrocyclotron is the isochronous cyclotron, which has a magnetic field that increases with radius, rather than with time. The de-focusing effect of this radial field gradient is compensated by ridges on the magnet faces which vary the field azimuthally as well. This allows particles to be accelerated continuously, on every period of the radio frequency, rather than in bursts as in most other accelerator types.

Related technologies

The spiraling of electrons in a cylindrical vacuum chamber within a transverse magnetic field is also employed in the magnetron, a device for producing high frequency radio waves (microwaves). The Synchrotron moves the particles through a path of constant radius, allowing it to be made as a pipe and so of much larger radius than is practical with the cyclotron and synchrocyclotron. The larger radius allows the use of numerous magnets, each of which imparts angular momentum and so allowing particles of higher velocity (mass) to be kept within the bounds of the evacuated pipe.

See also


- Beamline
- cyclotron radiation, synchrotron light or its close relative, bremsstrahlung radiation.
- electron cyclotron resonance
- Linear accelerator
- Particle accelerator
- Storage ring
- synchrocyclotron
- synchrotron

External links


- -- Method and apparatus for the acceleration of ions
- [http://user88.lbl.gov/88_home.html "The 88-Inch Cyclotron at LBNL"]
- [http://www.physics.rutgers.edu/cyclotron/ Rutgers Cyclotron] and
- [http://www.physicstoday.org/vol-57/iss-11/p30.html "Building a Cyclotron on a Shoestring"] Tim Koeth, now a graduate student at Rutgers University, built a 12-inch 1 MeV cyclotron as an undergraduate project, which is now used for a senior-level undergraduate and a graduate lab course.
- [http://www.phy.ntnu.edu.tw/java/cyclotron/cyclotron.html "Cyclotron java applet"]
- [http://www.niell.org/cyc2.html "Resonance Spectral Analysis with a Homebuilt Cyclotron"] an experiment done by Fred M. Niell, III his senior year of high school (1994-95) with which he won the overall grand prize in the ISEF.
- [http://casa.colorado.edu/~wcash/APS3730/chapter6.pdf Relativistic accelerator physics PDF]
- [http://www.wired.com/news/politics/0,1283,69726,00.html?tw=wn_tophead_1# Wired news article] about a neighborhood cyclotron in Anchorage, Alaska Category:Particle accelerators

Plutonium

Plutonium is a radioactive, metallic, chemical element. It has the symbol Pu and the atomic number 94. It is the element used in most modern nuclear weapons. The most important, albeit not most stable, isotope of plutonium is 239Pu, with a half-life of 24,110 years.

Notable characteristics

Plutonium is silvery in pure form, but has a yellow tarnish when oxidized. Peculiarly, the metal goes through phases of contraction as its temperature is increased. The heat given off by alpha particle emission makes plutonium warm to the touch in reasonable quantities; larger amounts can boil water. It displays four ionic oxidation states in aqueous solution:
- Pu3+ (blue lavender)
- Pu4+ (yellow brown)
- PuO2+ (pink orange)
- PuO+ (thought to be pink; this ion is unstable in solution and will disproportionate into Pu4+ and PuO2+; the Pu4+ will then oxidize the remaining PuO+ to PuO2+, being reduced in turn to Pu3+. Thus, aqueous solutions of plutonium tend over time towards a mixture of Pu3+ and PuO2+.)

Applications

The isotope Plutonium-239 is a key fissile component in modern nuclear weapons, due to its ease of fissioning and availability. The critical mass for an unreflected sphere of plutonium is 16 kg, but through the use of a neutron reflecting tamper the pit of plutonium in a fission bomb is reduced to 10 kg, which is a sphere with a diameter of 10 cm. Complete detonation of plutonium will produce an explosion of 20 kilotons of TNT per kilogram. (See also Nuclear Weapon Design.) Plutonium could also be used to manufacture radiological weapons or as a (not particularly deadly) poison. The plutonium isotope 238Pu is an alpha emitter with a half-life of 87 years. These characteristics make it well suited for electrical power generation for devices which must function without direct maintenance for timescales approximating a human lifetime. It is therefore used in RTGs such as those powering the Galileo and Cassini space probes; earlier versions of the same technology powered seismic experiments on the Apollo Moon missions. 238Pu has been used successfully to power artificial heart pacemakers, to reduce the risk of repeated surgery. It has been largely replaced by lithium-based batteries recharged by induction, but as of 2003 there were somewhere between 50 and 100 plutonium-powered pacemakers still implanted and functioning in living patients.

History

Initially predicted by Walter Russell, the production of plutonium and neptunium by bombarding uranium-238 with neutrons was predicted in 1940 by two teams working independently: Edwin M. McMillan and Philip Abelson at Berkeley Radiation Laboratory at the University of California, Berkeley and by Norman Feather & Egon Bretscher at the Cavendish Laboratory at University of Cambridge. Coincidentally both teams proposed the same names to follow on from uranium, like the sequence of the outer planets. Plutonium was first produced in 1941 by Dr. Glenn T. Seaborg, McMillan, J. W. Kennedy, and A. C. Wahl by deuteron bombardment of uranium in the 60-inch cyclotron at Berkeley, but the discovery was kept secret. It was named after the planet Pluto, having been discovered directly after neptunium (which itself was one higher on the periodic table than uranium), by analogy with the ordering of the planets in the solar system. During the Manhattan Project, large reactors were set up in Hanford, Washington for the production of plutonium, which was used in two of the first atomic bombs (the first was tested at Trinity site, the second dropped on Nagasaki, Japan). Large stockpiles of plutonium were built up by both the old Soviet Union and the United States during the Cold War—it was estimated that 300,000 kg of plutonium had been accumulated by 1982. Since the end of the Cold War, these stockpiles have become a focus of nuclear proliferation concerns. In 2002, the United States Department of Energy took possession of 34 metric tons of excess weapons grade plutonium stockpiles from the United States Department of Defense, and as of early 2003 was considering converting several nuclear power plants in the US from enriched uranium fuel to MOX fuel as a means of disposing of these. During the initial years after the discovery of plutonium, when its biological and physical properties were very poorly understood, a series of human radiation experiments were performed by the U.S. government and by private organizations acting on its behalf. During and after the end of World War II, scientists working on the Manhattan Project and other nuclear weapons research projects conducted studies of the effects of plutonium on laboratory animals and human subjects. In the case of human subjects, this involved injecting solutions containing (typically) five micrograms of plutonium into hospital patients thought to be either terminally ill, or to have a life expectancy of less than ten years either due to age or chronic disease condition. The injections were made without the informed consent of those patients. [http://library.lanl.gov/cgi-bin/getfile?00326640.pdf] The episode is now considered to be a serious breach of medical ethics and of the Hippocratic Oath, and has been sharply criticised as failing "both the test of our national values and the test of humanity." [http://www.thebulletin.org/article.php?art_ofn=nd99longworth]

Occurrence

While almost all plutonium is manufactured synthetically, extremely tiny trace amounts are found naturally in uranium ores. These come about by a process of neutron capture by 238U nuclei, initially forming 239U; two subsequent beta decays then form 239Pu (with a 239Np intermediary), which has a half-life of 24,100 years. This is also the process used to manufacture 239Pu in nuclear reactors. Some traces of 244Pu remain from the birth of the solar system from waste of supernovae, because its half-life (80 million yrs) is so long. A relatively high concentration of plutonium was discovered at the natural fission reactor in Oklo, Gabon in 1972. Since 1945, about 10 tons of plutonium have been released onto Earth through nuclear explosions.

Manufacture

The isotope Pu-239 is the key ingredient to most nuclear weapons. Its manufacture is therefore important to nuclear weapon states. Controlling or preventing the manufacture of refined Pu-239 is also important in preventing nuclear proliferation. Pu-239 is normally manufactured in nuclear reactors. If U-238 is exposed to neutron radiation, the nuclei will occasionally capture a neutron, becoming U-239. This happens more easily with fast neutrons than with slow neutrons, although both can be used. The U-239 rapidly undergoes beta decay to give Np-239, which rapidly undergoes a second beta decay, giving Pu-239. Fission activity is relatively rare, so even after significant exposure, the Pu-239 is still mixed with a great deal of U-238 (and possibly other isotopes of uranium, oxygen, other components of the original material, and fission products). The Pu-239 can then be chemically separated from the rest of the material to give high-purity Pu-239 metal. If Pu-239 captures a neutron, it becomes Pu-240. Pu-240 undergoes spontaneous fission at a relatively high rate. As a result, plutonium containing a significant fraction of Pu-240 is not well-suited to use in nuclear weapons; it emits neutron radiation, making handling more difficult, and its presence can lead to a "fizzle" in which a small explosion occurs, destroying the weapon but not causing fission of a significant fraction of the fuel. (The US has constructed a single experimental bomb using only reactor-grade plutonium.) Moreover, Pu-239 and Pu-240 cannot be chemically distinguished, so expensive and difficult isotope separation would be necessary to build a nuclear weapon using such a mix. Thus for the purposes of plutonium production, it is necessary to remove the U-238 frequently, before significant amounts of Pu-239 can be converted into Pu-240. A nuclear reactor that is used to produce plutonium must therefore have a means for exposing U-238 to neutron radiation, and for frequently rotating this U-238. A reactor running on unenriched or moderately enriched uranium naturally contains a great deal of U-238. However, most commercial power reactor designs require the entire reactor to shut down, often for weeks, in order to change the fuel elements. They therefore produce plutonium in a mix of isotopes that is not well-suited to weapon construction. Such a reactor could have machinery added that would permit U-238 slugs to be placed near the core and changed frequently, or it could be shut down frequently, so proliferation is a concern; for this reason, the IAEA inspects licensed reactors frequently. A few commercial power reactor designs, RBMK and CANDU, do permit refueling without shutdowns, and they therefore pose a proliferation risk. (In fact, the RBMK was built by the Soviet Union during the cold war, so despite their ostensibly peaceful purpose, it is likely that plutonium production was a design criterion.) Most plutonium is produced in research reactors or plutonium production reactors. Some production reactors are called breeder reactors because they produce more plutonium than they consume fuel; in principle, such reactors make extremely efficient use of natural uranium. In practice, their construction and operation is sufficiently difficult, and proliferation is a serious enough concern, that they are generally only used to produce plutonium. Plutonium reactors are generally (but not always) fast reactors, since fast neutrons are somewhat more efficient at plutonium production.

Compounds

Plutonium reacts readily with oxygen, forming PuO and PuO2, as well as intermediate oxides. It reacts with the halides, giving rise to compounds such as PuX3 where X can be F, Cl, Br or I; PuF4 is also seen. The following oxyhalides are observed: PuOCl, PuOBr and PuOI. It will react with carbon to form PuC, nitrogen to form PuN and silicon to form PuSi2.

Allotropes

silicon Even at ambient pressure, plutonium occurs in a variety of allotropes. These allotropes differ widely in crystal structure and density; the α and δ allotropes differ in density by more than 25% at the same volume. The presence of these many allotropes makes machining plutonium very difficult, as it changes state very readily. The reasons for the complicated phase diagram are not entirely understood; recent research has focused on constructing accurate computer models of the phase transitions. In weapons applications, plutonium is often alloyed with another metal (e.g., delta phase with a small percentage of gallium) to increase phase stability and thereby enhance workability and ease of handling. Interestingly, in fission weapons, the explosive shock waves used to compress a plutonium core will also cause a transition from the usual delta phase plutonium to the denser alpha phase, significantly helping to achieve supercriticality.

Isotopes

Twenty-one plutonium radioisotopes have been characterized. The most stable are Pu-244, with a half-life of 80.8 million years, Pu-242, with a half-life of 373,300 years, and Pu-239, with a half-life of 24,110 years. All of the remaining radioactive isotopes have half-lives that are less than 7,000 years. This element also has eight meta states, though none are very stable (all have half-lives less than one second). The isotopes of plutonium range in atomic weight from 228.0387 u (Pu-228) to 247.074 u (Pu-247). The primary decay modes before the most stable isotope, Pu-244, are spontaneous fission and alpha emission; the primary mode after is beta emission. The primary decay products before Pu-244 are uranium and neptunium isotopes (neglecting the wide range of daughter nuclei created by fission processes), and the primary products after are americium isotopes. Key isotopes for applications are Pu-239, which is suitable for use in nuclear weapons and nuclear reactors, and Pu-238, which is suitable for use in radioisotope thermoelectric generators; see above for more details. The isotope Pu-240 undergoes spontaneous fission very readily, and is produced when Pu-239 is exposed to neutrons. The presence of Pu-240 in a material limits its nuclear bomb potential since it emits neutrons randomly, increasing the difficulty of initiating accurately the chain reaction at the good instant and thus reducing the bomb's reliability and power. Plutonium consisting of more than about 90% Pu-239 is called weapon-grade plutonium; plutonium obtained from commercial reactors generally contains at least 20% Pu-240 and is called reactor-grade plutonium.

Precautions

All isotopes and compounds of plutonium are toxic and radioactive. While plutonium is sometimes described in media reports as "the most toxic substance known to man", there is general agreement among experts in the field that this is incorrect. As of 2003, there has yet to be a single human death officially attributed to plutonium exposure. Naturally-occurring radium is about 200 times more radiotoxic than plutonium, and some organic toxins like Botulin toxin are still more toxic. Botulin toxin, in particular, has a lethal dose of 300pg/kg, far less than the quantity of plutonium that poses a significant cancer risk. In addition, beta and gamma emitters (including the C-14 and K-40 in nearly all food) can cause cancer on casual contact, which alpha emitters cannot. Orally, plutonium is less toxic (non-oncogenically speaking) than several common substances, including caffeine, acetaminophen, some vitamins, pseudoephedrine, and any number of plants and fungi. It is perhaps somewhat more toxic than pure ethanol, but less so than tobacco and many illegal drugs (some such as marijuana are negligibly toxic). From a purely chemical standpoint, its toxicity is probably on par with lead and other heavy metals. That said, there is no doubt that plutonium may be extremely dangerous when handled incorrectly. The alpha radiation it emits does not penetrate the skin, but can irradiate internal organs when plutonium is inhaled or ingested. Particularly at risk are the skeleton, onto the surface of which it is likely to be absorbed, and the liver, where it will collect and become concentrated. Extremely fine particles of plutonium (on the order of micrograms) can cause lung cancer if inhaled into the lungs. Other substances including ricin, botulinum toxin and tetanus toxin are fatal in doses of (sometimes far) under one milligram, and others (the nerve agents, the amanita toxin, the fugu toxin) are in the range of a few milligrams. As such, plutonium is not unusual in terms of toxicity, even by inhalation. In addition, those substances are fatal in hours to days, whereas plutonium (and other cancer-causing radioactives) give an increased chance of illness decades in the future. Considerably larger amounts may cause acute radiation poisoning and death if ingested or inhaled; however, so far, no human is known to have immediately died because of inhaling or ingesting plutonium and many people have measurable amounts of plutonium in their bodies. It must be noted, however, that in contrast to naturally occurring radioisotopes such as radium or C-14, plutonium was manufactured, concentrated, and isolated in large amounts (hundreds of metric tons) during the Cold War for weapons production. These piles, whether in weapons form or otherwise, could pose a significant toxicologic risk, largely because, unlike chemical or biological agents, there is no practical way to destroy them. Toxicity issues aside, care must be taken to avoid the accumulation of amounts of plutonium which approach critical mass. Despite not being confined by external pressure as is required for a nuclear weapon, it will nevertheless heat itself and break whatever confining environment it is in. Shape is relevant; compact shapes such as spheres are to be avoided. Plutonium in solution is more likely to form a critical mass than the solid form. A weapon-scale nuclear explosion cannot occur accidentally, since it requires a greatly supercritical mass in order to explode rather than simply melt or fragment. However, a marginally critical mass will cause a lethal dose of radiation and has in fact done so in the past on several occasions. Multiple criticality accidents have occurred in the past at least in the US and the former USSR, some of them with lethal consequences. Careless handling of tungsten carbide bricks around a 6.2 kg plutonium sphere resulted in a lethal dose of radiation at Los Alamos on August 21, 1945, when scientist Harry Daghlian received a dose estimated to be 510 rems (5.1 Sv) and died four weeks later. Nine months later, another Los Alamos scientist, Louis Slotin, died from a similar accident involving a beryllium reflector and the exact same plutonium core (the so-called “demon core”) that had previously claimed the life of Daghlian. In 1958, during a process of purifying plutonium at Los Alamos, a critical mass was formed in a mixing vessel, which resulted in the death of a crane operator. Other accidents of this sort have occurred in the Soviet Union, Japan, and many other countries. (See List of nuclear accidents) Metallic plutonium is also a fire hazard, especially if the material is finely divided. It reacts chemically with oxygen and water which may result in an accumulation of plutonium hydride, a pyrophoric substance; that is, a material that will ignite in air at room temperature. Plutonium expands considerably in size as it oxidizes and thus may break its container. The radioactivity of the burning material is an additional hazard. Magnesium oxide sand is the most effective material for extinguishing a plutonium fire. It cools the burning material, acting as a heat sink, and also blocks off oxygen. Water is also effective. There was a major plutonium-initiated fire at the Rocky Flats Plant near Boulder, Colorado in 1969 [http://tis.eh.doe.gov/techstds/standard/hdbk1081/hbk1081f.html#ZZ39]. To avoid these problems, special precautions are necessary to store or handle plutonium in any form; generally a dry inert atmosphere is required [http://tis.eh.doe.gov/techstds/standard/hdbk1081/hbk1081d.html#ZZ28].

See also


- LD50
- lethal dose

References


- [http://periodic.lanl.gov/elements/94.html Los Alamos National Laboratory - Plutonium]
- [http://education.jlab.org/itselemental/ele094.html It's Elemental - Plutonium]
- [http://www.webelements.com/webelements/elements/text/Pu/index.html WebElements.com - Plutonium]
- [http://environmentalchemistry.com/yogi/periodic/Pu.html EnvironmentalChemistry.com - Plutonium] (JavaScript required)
- [http://www.fas.org/nuke/intro/nuke/plutonium.htm Federation of American Scientists - Plutonium production]
- [http://nuclearweaponarchive.org/Library/Plutonium/ nuclearweaponarchive.org - Plutonium Manufacture and Fabrication]
- [http://www.edpsciences.org/journal/index.cfm?v_url=epl/full/2001/16/6673/6673.html Ambient pressure phase diagram of plutonium - A unified theory for α-Pu and δ-Pu], P. Söderlind, Europhys. Lett., 55 (4), p. 525 (2001).

External links


- [http://www.llnl.gov/csts/publications/sutcliffe/ "A Perspective on the Dangers of Plutonium" by Lawrence Livermore National Laboratory]
- [http://www.ccnr.org/index_plute.html collection of articles on plutonium at the Canadian Coalition for Nuclear Responsibility]
- [http://russp.org/BLC-3.html The Myth of Plutonium Toxicity]
- [http://www.lanl.gov/worldview/news/releases/archive/00-099.shtml Criticality Accidents Report Issued]
- [http://www.nuclearfiles.org/menu/key-issues/nuclear-weapons/issues/accidents/ Nuclear Accidents Timeline]
- [http://www.globalsecurity.org/wmd/library/report/crs/97-564.htm Nuclear Weapons: Disposal Options for Surplus Weapons-Usable Plutonium]
- [http://www-cms.llnl.gov/s-t/pu-phase_diagram.html Unraveling the Phase Diagram of Plutonium]
- [http://www.ieer.org/fctsheet/pu-props.html Physical, Nuclear, and Chemical, Properties of Plutonium] from IEER Category:Actinides Category:Chemical elements Category:Nuclear materials ko:플루토늄 ja:プルトニウム th:พลูโทเนียม

Berkelium

Berkelium is a synthetic element in the periodic table that has the symbol Bk and atomic number 97. A radioactive metallic element in the actinide series, berkelium was first synthesized by bombarding americium with alpha particles (helium ions) and was named after Berkeley, California. Berkelium was the fifth transuranic element to be synthesized.

Notable characteristics

Weighable amounts of berkelium-249 (half-life 314 days) make it possible to determine some of its properties using macroscopic quantities. As of 2004 it had not been isolated in its elemental form, but it is predicted to be a silvery metal that would easily oxidize in air at elevated temperatures and would be soluble in dilute mineral acids. X-ray diffraction techniques have been used to identify various berkelium compounds such as berkelium dioxide (BkO2), berkelium fluoride (BkF3), berkelium oxychloride (BkOCl), and berkelium trioxide (BkO3). In 1962 visible amounts of berkelium chloride were isolated that weighed 3 billionths of a gram. This was the first time visible amounts of a pure berkelium compound were produced. Like other actinides, berkelium bio-accumulates in skeletal tissue. This element has no known uses outside of basic research and plays no biological role.

History

Berkelium was first synthesized by Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, and Kenneth Street, Jr at the University of California, Berkeley in December 1949. The team used a cyclotron to bombard a milligram-sized target of americium-241 with alpha particles to produce berkelium-243 (half-life 4.5 hours) and two free neutrons. One of the longest lived isotopes of the element, berkelium-249 (half-life 320 days), was later synthesized by subjecting a curium-244 target with an intense beam of neutrons.

Isotopes

19 radioisotopes of berkelium have been characterized, with the most stable being Bk-247 with a half-life of 1380 years, Bk-248 with a half-life of >9 years, and Bk-249 with a half-life of 320 days. All of the remaining radioactive isotopes have half-lifes that are less than 5 days, and the majority of these have half lifes that are less than 5 hours. This element also has 2 meta states, with the most stable being Bk-248m (t½ 23.7 hours). The isotopes of berkelium range in atomic weight from 235.057 amu (Bk-235) to 254.091 amu (Bk-254).

References


- [http://periodic.lanl.gov/elements/97.html Los Alamos National Laboratory - Berkelium]
- [http://education.jlab.org/itselemental/ele097.html It's Elemental - Berkelium]

External links


- [http://www.webelements.com/webelements/elements/text/Bk/index.html WebElements.com - Berkelium] Category:Chemical elements Category:Actinides Category:University of California, Berkeley ja:バークリウム th:เบอร์คีเลียม

Californium

Californium is a synthetic element in the periodic table that has the symbol Cf and atomic number 98. A radioactive transuranic element, californium has very few uses and was discovered by bombarding curium with alpha particles (helium ions).

Notable characteristics

Weighable amounts of californium make it possible to determine some of its properties using macroscopic quantities. Californium-252 (2.6 year half-life) is a very strong neutron emitter and is thus extremely radioactive and harmful (one microgram spontaneously emits 170 million neutrons per minute). The decay of californium-254 (55-day half-life) may have been detected through telescopes in supernovae remnants. Californium-249 is formed from the beta decay of berkelium-249 and most other californium isotopes are made by subjecting berkelium to intense neutron radiation in a nuclear reactor. The element does have some specialist applications dealing with its radioactivity but otherwise is largely too difficult to produce to have widespread useful significance as a material. Some of its uses are:
- neutron startup source for some nuclear reactors, calibrating instrumentation
- treatment of certain cervical and brain cancers where other radiation therapy is ineffective
- radiography of aircraft to detect metal fatigue
- airport neutron-activation detectors of explosives
- neutron moisture gauges used to find water and petroleum layers in oil wells
- portable neutron source in gold and silver prospecting for on-the-spot analysis As of 2004, californium has not been isolated in its metallic form. The only californium ion that is stable in aqueous solution is californium (III). Californium has no biological role and only a few californium compounds have been made and studied. Included among these are: californium oxide (CfO3), californium trichloride (CfCl3) and californium oxychloride (CfOCl). Californium-251 is famous for having a very small critical mass, high lethality, and short period of toxic environmental irradiation relative to radioactive elements commonly used for radiation explosive weaponry, creating speculation about possible use in pocket nukes although this urban legend is unfounded since it would be very difficult to make a Californium-251 bomb weighing less than 2 kg and the costs of such a bomb would be prohibitive. Other weaponry uses, such as showering an area with Californium, are not impossible but are seen as inhumane and are subject to inclement weather conditions and porous terrain considerations. Often cited as a consideration is the cost of producing Californium en masse, but the cost citations are usually due to extra fees that laboratory materials companies insert for sake of caution and market needs. A government needn't consider these as prohibitive.

History

Californium was first synthesized by University of California, Berkeley researchers Stanely Thompson, Kenneth Street, Jr., Albert Ghiorso and Glenn T. Seaborg in 1950. It was the sixth transuranium element to be discovered and the team announced their discovery on March 17, 1950. It was named after the U.S. state of California and for the University of California, Berkeley (which is nicknamed "Cal"). To produce element 98, the team bombarded a microgram-sized target of curium-242 with 35 MeV alpha particles in the 60-inch Berkeley cyclotron which produced atoms of californium-245 (half-life 44 minutes) and a free neutron.

Isotopes

19 radioisotopes of californium have been characterized, with the most stable being Cf-251 with a half-life of 898 years, Cf-249 with a half-life of 351 years, and Cf-250 with a half-life of 13 years. All of the remaining radioactive isotopes have half-lifes that are less than 2.7 years, and the majority of these have half lifes that are less than 20 minutes. The isotopes of californium range in atomic weight from 237.062 amu (Cf-237) to 256.093 amu (Cf-256).

References


- [http://periodic.lanl.gov/elements/98.html Los Alamos National Laboratory - Californium]
- [http://education.jlab.org/itselemental/ele098.html It's Elemental - Californium]
- Guide to the Elements - Revised Edition, Albert Stwertka, (Oxford University Press; 1998) ISBN 0-19-508083-1 Californium has no biological role

External links


- [http://www.webelements.com/webelements/elements/text/Cf/index.html WebElements.com - Californium]
- [http://www.nuclearweaponarchive.org/Nwfaq/Nfaq6.html#nfaq6.2 NuclearWeaponArchive.org - Californium] Category:Chemical elements Category:Actinides Category:University of California, Berkeley ja:カリホルニウム th:แคลิฟอร์เนียม
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