Стэнфорд аймақтық жеделдеткіш орталығы: зерттеулер мен жаңалықтар

Research center at Stanford University

SLAC National Accelerator Laboratory, originally named the Stanford Linear Accelerator Center, is a federally funded research and development center in Menlo Park, California, United States. Founded in 1962, the laboratory is now sponsored by the United States Department of Energy and administrated by Stanford University. It is the site of the Stanford Linear Accelerator, a 3.2 kilometer (2 mile) linear accelerator constructed in 1966 that could accelerate electrons to energies of 50 GeV. Today SLAC research centers on a broad program in atomic and solid state physics, chemistry, biology, and medicine using X rays from synchrotron radiation and a free electron laser as well as experimental and theoretical research in elementary particle physics, astroparticle physics, and cosmology. The laboratory is under the programmatic direction of the United States Department of Energy Office of Science.

The main accelerator was an RF linear accelerator that accelerated electrons and positrons up to 50 GeV. At long, the accelerator was the longest linear accelerator in the world, and was claimed to be "the world's most straight object." until 2017 when the European x ray free electron laser opened. The main accelerator is buried 9.14 m below ground and passes underneath Interstate Highway 280. The above ground klystron gallery atop the beamline, was the longest building in the United States until the LIGO project's twin interferometers were completed in 1999. It is easily distinguishable from the air and is marked as a visual waypoint on aeronautical charts. A portion of the original linear accelerator is now part of the Linac Coherent Light Source.

The Stanford Linear Collider was a linear accelerator that collided electrons and positrons at SLAC. The center of mass energy was about 90 GeV, equal to the mass of the Z boson, which the accelerator was designed to study. Grad student Barrett D. Milliken discovered the first Z event on 12 April 1989 while poring over the previous day's computer data from the Mark II detector. The bulk of the data was collected by the SLAC Large Detector, which came online in 1991. Although largely overshadowed by the Large Electron–Positron Collider at CERN, which began running in 1989, the highly polarized electron beam at SLC (close to 80%) made certain unique measurements possible, such as parity violation in Z Boson b quark coupling. Presently no beam enters the south and north arcs in the machine, which leads to the Final Focus, therefore this section is mothballed to run beam into the PEP2 section from the beam switchyard.

The SLAC Large Detector (SLD) was the main detector for the Stanford Linear Collider. It was designed primarily to detect Z bosons produced by the accelerator's electron positron collisions. Built in 1991, the SLD operated from 1992 to 1998.

PEP (Positron Electron Project) began operation in 1980, with center of mass energies up to 29 GeV. At its apex, PEP had five large particle detectors in operation, as well as a sixth smaller detector. About 300 researchers made used of PEP. PEP stopped operating in 1990, and PEP II began construction in 1994.

From 1999 to 2008, the main purpose of the linear accelerator was to inject electrons and positrons into the PEP II accelerator, an electron positron collider with a pair of storage rings in circumference. PEP II was host to the BaBar experiment, one of the so called B Factory experiments studying charge parity symmetry.

The Stanford Synchrotron Radiation Lightsource (SSRL) is a synchrotron light user facility located on the SLAC campus. Originally built for particle physics, it was used in experiments where the J/ψ meson was discovered. It is now used exclusively for materials science and biology experiments which take advantage of the high intensity synchrotron radiation emitted by the stored electron beam to study the structure of molecules. In the early 1990s, an independent electron injector was built for this storage ring, allowing it to operate independently of the main linear accelerator.

SLAC plays a primary role in the mission and operation of the Fermi Gamma ray Space Telescope, launched in August 2008. The principal scientific objectives of this mission are:
To understand the mechanisms of particle acceleration in AGNs, pulsars, and SNRs. To resolve the gamma ray sky: unidentified sources and diffuse emission. To determine the high energy behavior of gamma ray bursts and transients. To probe dark matter and fundamental physics.

The Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) is partially housed on the grounds of SLAC, in addition to its presence on the main Stanford campus.

The Stanford PULSE Institute (PULSE) is a Stanford Independent Laboratory located in the Central Laboratory at SLAC. PULSE was created by Stanford in 2005 to help Stanford faculty and SLAC scientists develop ultrafast x ray research at LCLS. PULSE research publications can be viewed here.

The Linac Coherent Light Source (LCLS) is a free electron laser facility located at SLAC. The LCLS is partially a reconstruction of the last 1/3 of the original linear accelerator at SLAC, and can deliver extremely intense x ray radiation for research in a number of areas. It achieved first lasing in April 2009. The laser produces hard X rays, 109 times the relative brightness of traditional synchrotron sources and is the most powerful x ray source in the world. LCLS enables a variety of new experiments and provides enhancements for existing experimental methods. Often, x rays are used to take "snapshots" of objects at the atomic level before obliterating samples. The laser's wavelength, ranging from 6.2 to 0.13 nm (200 to 9500 electron volts (eV)) is similar to the width of an atom, providing extremely detailed information that was previously unattainable. Additionally, the laser is capable of capturing images with a "shutter speed" measured in femtoseconds, or million billionths of a second, necessary because the intensity of the beam is often high enough so that the sample explodes on the femtosecond timescale.

In 2012, the first two thirds (~2 km) of the original SLAC LINAC were recommissioned for a new user facility, the Facility for Advanced Accelerator Experimental Tests (FACET). This facility was capable of delivering 20 GeV, 3 nC electron (and positron) beams with short bunch lengths and small spot sizes, ideal for beam driven plasma acceleration studies. The facility ended operations in 2016 for the constructions of LCLS II which will occupy the first third of the SLAC LINAC. The FACET II project will re establish electron and positron beams in the middle third of the LINAC for the continuation of beam driven plasma acceleration studies in 2019.

The Next Linear Collider Test Accelerator (NLCTA) is a 60 120 MeV high brightness electron beam linear accelerator used for experiments on advanced beam manipulation and acceleration techniques. It is located at SLAC's end station B. A list of relevant research publications can be viewed here .

SLAC also performs theoretical research in elementary particle physics, including in areas of quantum field theory, collider physics, astroparticle physics, and particle phenomenology.

SLAC has also been instrumental in the development of the klystron, a high power microwave amplification tube. There is active research on plasma acceleration with recent successes such as the doubling of the energy of 42 GeV electrons in a meter scale accelerator. There was a Paleoparadoxia found at the SLAC site, and its skeleton can be seen at a small museum there in the Breezeway. The SSRL facility was used to reveal hidden text in the Archimedes Palimpsest. X rays from the synchrotron radiation lightsource caused the iron in the original ink to glow, allowing the researchers to photograph the original document that a Christian monk had scrubbed off.