514 research outputs found
Experimental physics at JLab: Where confinement meets asymptotic freedom
Physics and technological highlights of the current and near future activities of the Italian JLab12 collaboration working at the Jefferson National Accelerator Facility are shortly summarized
The CLAS12 large area RICH detector
Abstract A large area RICH detector is being designed for the CLAS12 spectrometer as part of the 12 GeV upgrade program of the Jefferson Lab Experimental Hall-B. This detector is intended to provide excellent hadron identification from 3 GeV/ c up to momenta exceeding 8 GeV/ c and to be able to work at the very high design luminosity-up to 10 35 cm 2 s −1 . Detailed feasibility studies are presented for two types of radiators, aerogel and liquid C 6 F 14 freon, in conjunction with a highly segmented light detector in the visible wavelength range. The basic parameters of the RICH are outlined and the resulting performances, as defined by preliminary simulation studies, are reported
Monte Carlo studies for medical imaging detector optimization
This work reports on the Monte Carlo optimization studies of detection systems for Molecular Breast Imaging with radionuclides and Bremsstrahlung Imaging in nuclear medicine. Molecular Breast Imaging requires competing performances of the detectors: high efficiency and high spatial resolutions; in this direction, it has been proposed an innovative device which combines images from two different, and somehow complementary, detectors at the opposite sides of the breast. The dual detector design allows for spot compression and improves significantly the performance of the overall system if all components are well tuned, layout and processing carefully optimized; in this direction the Monte Carlo simulation represents a valuable tools. In recent years, Bremsstrahlung Imaging potentiality in internal radiotherapy (with beta-radiopharmaceuticals) has been clearly emerged; Bremsstrahlung Imaging is currently performed with existing detector generally used for single photon radioisotopes. We are evaluating the possibility to adapt an existing compact gamma camera and optimize by Monte Carlo its performance for Bremsstrahlung imaging with photons emitted by the beta- from 90 Y
Tracking system based on GEM chambers
GEM chambers are becoming one of the best technology for charge particle tracking fulfilling the challenging requirements of modern experiment at intermediate and high energy, including Parity Violation Electron Scattering experiments. GEM tracker combines high spatial resolution, large active area and pretty good tolerance to high particle flux, at reasonable cost. GEM technology is shortly
presented and a specific application for the high luminosity experiments in Hall A at JLab is discussed. Some alternatives to the GEM are also addressed
Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of theta(p)(cm) cm = 70 degrees. The longitudinal transfer K-LL, measured to be 0.645 +/- 0.059 +/- 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is similar to 3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude
Optimization of the gas flow in a GEM chamber and development of the GEM foil stretcher
The gas electron multiplier technology has been proven to tolerate rat e
larger than 50 MHz/cm2 without noticeable aging and to provide sub resolution
on working chambers up to 45 cm x 45 cm. A new gas electron multiplier-based
tracker is under development for the Hall A upgrade at Jefferson Lab. The
chambers of the tracker have been designed in a modular way: each chamber
consists of 3 adjacent gas electron multiplier modules, with an active area
of 40 cm x 50 cm each. We optimized the gas flow inside the gas electron
multiplier module volume, using the COMSOL physics simulator framework; the
COMSOL-based analysis includes the design of the inlet and outlet pipes and
the maximization of the uniformity of the gas flow. We have defined the
procedures for the assembling of the gas electron multiplier modules and
designed a mechanical system (TENDIGEM) that will be used to stretch the GEM
foils at the proper tension (few kg/cm); the TENDIGEM is based on the
original design developed at LNF
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