120827387
A measurement of A20 (1320) formation in photon photon collisions
120023840
Study of two photon production of rho0 omega in e+ e- interactions
125894282
BOSE-EINSTEIN CORRELATIONS OF PIONS IN e+ e-ANNIHILATION AT 29-GeV CENTER-OF-MASS ENERGY
123222571
Measurement of the photon structure function F(2) (gamma) (X, Q**2) between 10-GEV**2 < Q**2 < 60-GEV**2
121878723
Studies of parton fragmentation and baryon production with the TPC at PEP
Results are presented from the TPC on the analysis of 3-jet events, on the width of gluon jets versus quark jets, and on proton and lambda production and correlations.
123050118
$f1(1285)$ formation in photon photon fusion reactions
Abstract We have observed formation of the f 1 (1285) in the reaction e + e - →e + e - π + π - η ( η → γγ ). Its γγ ∗ width is determined in several Q 2 bins. The γγ coupling parameter for the f 1 (1285) is found to be 2.4±0.5±0.5 keV. This value is compared to that for the X (1420), another J =1 state formed in γγ fusion reactions, which may belong to the same meson nonet.
108485009
THE ELECTRON-RING ACCELERATOR PROGRAM AT LRL
A progress report is presented on the activities at LRL in connection with electron-ring accelerators. A two-stage compressor unit (employing only low-intensity beams) has been built, and operated with a 4-MeV 100-mA linac as an injector. Electron rings have been formed and compressed from 20 cm radius to 7 cm radius. A three-stage compression unit has been constructed and is now under test with the high intensity (200 A) 3.3-MeV beam of the Astron injector. The apparatus is described. Design work on a magnetic expansion unit is reported.
41238054
PEP Insertion Quadrupole Design Features
The insertion quadrupoles for the PEP storage ring must have a very uniform gradient to focus the circulating beams to a very small size at the interaction point for high luminosity. Quads have been built which achieve the desired field within the full pole aperture radius to approximately one part in 104. The design features which permitted this achievement are described.
31650636
Improving the Bevatron Vacuum to 10-10 Torr
Pressure of ~10-10 torr is needed in the Bevatron to accelerate partially-stripped very-heavy ions (e.g. U69+) in the Bevatron without significant loss due to interactions with the residual gas. This ultra-high vacuum will be achieved by installing (summer and fall 1981) a cryogenic liner, mostly 12°K, surrounding the Bevatron circulating beam. The novel construction features are presented along with results from successful tests of prototype sections. This is believed to be the largest application of cryogenic pumping to particle accelerators yet undertaken.
38762481
The PEP Injection System
A system to transport 10-to-15-GeV electron and positron beams from the Stanford Linear Accelerator and to inject them into the PEP storage ring under a wide variety of lattice configurations has been designed. Optically, the transport line consists of three 360° phase-shift sections of FODO lattice, with bending magnets interspersed in such a way as to provide achromaticity, convenience in energy and emittance definition, and independent tuning of the various optical parameters for matching into the ring. The last 360° of phase shift has 88 milliradians of bend in a vertical plane and deposits the beam at the injection septum via a Lambertson magnet. Injection is accomplished by launching the beam with several centimeters of radial betatron amplitude in a fast bump provided by a triad of pulsed kicker magnets. Radiation damping reduces the collective amplitude quickly enough to allow injection at a high repetition rate.
121592881
Thermal problems on high flux beam lines
Abstract Wiggler and undulator magnets can provide very intense photon flux densities to beam line components. This paper addresses some thermal/materials consequences due to such impingement. The LBL/Exxon/SSRL hybrid-wiggler beam line VI [1] now nearing operation will be able to provide up to ∼ 7 kW of total photon power at planned SPEAR operating conditions. The first masks are located at 6.5 m from the source and may receive a peak power density (transverse to the beam) exceeding 20 kW/cm2. Significantly, this heat transfer rate exceeds that radiated from the sun's surface (7 kW/cm2) and is comparable to that if welding torches. Clearly, cooling and configuration are of critical importance. Configurations for the first mask, the movable mask and the pivot mask on this beam line are presented together with considerations of thermal stress fatigue and of heat transfer by conduction to water-cooling circuits. Some preliminary information on the heating of crystals and mirrors is also presented. For the future, many additional intense wiggler/undulator beam lines are contemplated at several storage rings. The design of these beamlines would be enhanced by faster and more accurate computational techniques. LBL is developing a computer code which will be capable of giving photon power densities onto impinged surfaces for a wide range of source and beam line parameters. These include electron beam energy, current, emittance and orbit deviations; wiggler/undulator length, period and magnetic field; photon energy and angular distribution; reflection/absorption at intermediate impinged surfaces; defining apertures and focusing by mirrors. Three-dimensional computer programs for temperature, stress and strain have been available for some years, but “user friendly” versions are being sought. Other items to pursue are also suggested.