The acceleration of electrons to approximately 0.8 GeV has been observed in a self-injecting laser wakefield accelerator driven at a plasma density of 5.5x10(18) cm(-3) by a 10 J, 55 fs, 800 nm laser ...pulse in the blowout regime. The laser pulse is found to be self-guided for 1 cm (>10zR), by measurement of a single filament containing >30% of the initial laser energy at this distance. Three-dimensional particle in cell simulations show that the intensity within the guided filament is amplified beyond its initial focused value to a normalized vector potential of a0>6, thus driving a highly nonlinear plasma wave.
The spin precession frequency of muons stored in the (g-2) storage ring has been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT violation signatures were searched for a ...nonzero delta omega a(=omega a mu+ - omega a mu-) and a sidereal variation of omega a mu+/-). No significant effect is found, and the following limits on the standard-model extension parameters are obtained: bZ = -(1.0+/-1.1) x 10(-23) GeV; (m mu dZ0 + HXY)=(1.8+/-6.0) x 10(-23) GeV; and the 95% confidence level limits b perpendicular mu+ <1.4 x 10(-24) GeV and b perpendicular mu- <2.6 x 10(-24) GeV.
The CLEO III drift chamber Peterson, D; Berkelman, K; Briere, R ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2002, Letnik:
478, Številka:
1
Journal Article
Recenzirano
The CLEO group at the Cornell Electron Storage Ring has constructed and commissioned a new central drift chamber. With 9796 cells arranged in 47 layers ranging in radius from 13.2 to
79
cm
, the new ...drift chamber has a smaller outer radius and fewer wires than the drift chamber it replaces, but allows the CLEO tracking system to have improved momentum resolution. Reduced scattering material in the chamber gas and in the inner skin separating the drift chamber from the silicon vertex detector provides a reduction of the multiple scattering component of the momentum resolution and an extension of the usable measurement length into the silicon. Momentum resolution is further improved through quality control in wire positioning and symmetry of the electric fields in the drift cells which have provided a reduction in the spatial resolution to
88
μm
(averaged over the full drift range).
The generation of quasimonoenergetic electron beams, with energies greater than 500 MeV, in a laser-plasma accelerator driven by 2.5 J, 80 fs laser pulses guided in a low density plasma channel, is ...investigated. The laser energy required to achieve electron injection is found to depend strongly on the quality of the input laser focal spot. Simulations show that, although the matched spot size of the plasma channel is greater than the self-focused spot size, the channel assists relativistic self-focusing and enables electron injection to occur at lower plasma densities and laser powers than would be possible without a waveguide.
The Brookhaven muon storage ring magnet Danby, G.T.; Addessi, L.; Armoza, Z. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2001, Letnik:
457, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The muon g-2 experiment at Brookhaven National Laboratory has the goal of determining the muon anomalous
g-value
a
μ
(=(g−2)/2)
to the very high precision of 0.35 parts per million and thus requires ...a storage ring magnet with great stability and homogeniety. A superferric storage ring with a radius of 7.11 m and a magnetic field of 1.45 T has been constructed in which the field quality is largely determined by the iron, and the excitation is provided by superconducting coils operating at a current of 5200 A. The storage ring has been constructed with maximum attention to azimuthal symmetry and to tight mechanical tolerances and with many features to allow obtaining a homogenous magnetic field. The fabrication of the storage ring, its cryogenics and quench protection systems, and its initial testing and operation are described.
A higher precision measurement of the anomalous g value, a(mu)=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year ...2000. The result a(mu(+))=11 659 204(7)(5)x10(-10) (0.7 ppm) is in good agreement with previous measurements and has an error about one-half that of the combined previous data. The present world average experimental value is a(mu)(expt)=11 659 203(8)x10(-10) (0.7 ppm).
A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x ...10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.
Electromagnetic calorimeters for the BNL muon ( g−2) experiment Sedykh, S.A; Blackburn, J.R; Bunker, B.D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2000, Letnik:
455, Številka:
2
Journal Article
Recenzirano
A set of 24 lead/scintillating fiber electromagnetic calorimeters has been constructed for the new muon (
g−2) experiment at the Brookhaven AGS. These calorimeters were designed to provide very good ...energy resolution for electrons up to 3 GeV while also yielding excellent timing information. Special requirements in the experiment related to the uniformity of response, the short-term gain and timing stability, and the neutron background led to several unusual design features. The calorimeters were tested and calibrated with electrons in the energy range 0.5–4.0 GeV and have been installed and used in the muon storage ring. The design criteria, construction, and performance of the system are described.
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