121196804
CERN beam test of silicon-tungsten calorimeter test module
PIN diode silicon sensors with low leakage current were developed as 4×4 pixel arrays from 5 inch wafers. A test module of silicon-tungsten calorimeter was designed, built using the sensors, and tested with high energy beam of electron, muon, and hadrons for the study of its application at the future linear collider. The construction of the test module and the results of the beam test are discussed.
120829108
NaI (Tl) Calorimeter Calibration and Simulation for Coulomb Sum Rule Experiment in Hall-A at Jefferson Lab
A precision measurment of inclusive electron scattering cross sections is carried out at Jefferson Lab in the quasi-elastic region for 4He, 12C, 56Fe and 208Pb targets. The longitudinal (RL) and transverse (RT) response functions of the nucleon need to be extracted precisely in the momentum transfer range 0.55 GeV/c ≤ |q| ≤ 1.0 GeV/c. To achieve the above goal, a NaI (Tl) calorimeter is used to distinguish good electrons from background, including pions and low energy electrons rescattered from the walls of the spectrometer magnets. Due to a large set of kinematics and changes in HV settings, a number of calibrations are performed for the NaI (Tl) detector. Corrections for a few blocks of NaI (Tl) with bad or no signal are applied. The resolution of the NaI (Tl) detector after calibration reached at E = 1 GeV. The performance of the NaI (Tl) detector is compared with a simulation. The good calibration and background analysis for the NaI(Tl) detector are very important for the reduction of the systematic error of cross sections and the separation of RL and RT.
119303854
Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube
Abstract We have studied the afterpulse of a hemispherical photomultiplier tube for an upcoming reactor neutrino experiment. The timing, the amplitude, and the rate of the afterpulse for a 10 in. photomultiplier tube were measured with a 400 MHz FADC up to 16 μ s time window after the initial signal generated by an LED light pulse. The time and amplitude correlation of the afterpulse shows several distinctive groups. We describe the dependencies of the afterpulse on the applied high voltage and the amplitude of the main light pulse. The present data could shed light upon the general mechanism of the afterpulse.
7161710
Photoproduction of phi meson from proton: Polarization observables and the strangeness in the nucleon
The polarization observables in phi meson photoproduction is studied to probe the strangeness content of the nucleon. In addition to the dominant diffractive production and the one-pion-exchange process, we take into account the direct knockout mechanism that arises from the possible hidden strangeness content of the nucleon. We find that some double polarization observables are very sensitive to the strangeness content of the proton because of the different spin structures of the amplitudes associated with different mechanisms. This suggests that such measurements could be very useful in probing the strangeness content in the proton. The orbitally excited quark-cluster configurations in the proton are included in the calculation and found to have little effect.
118319438
Scalar kappa meson in K* photoproduction
We propose that the scalar $\kappa(800)$ meson may play an important role in $K^*$ photoproduction. In the reactions of $\gamma p \to K^{*+} \Lambda$ and $\gamma p \to K^{*0} \Sigma^+$, we consider the production mechanisms including $t$-channel $K^*$, $K$, $\kappa$ exchanges, s-channel $N$, $\Delta$ diagrams, and $u$-channel $\Lambda$, $\Sigma$, $\Sigma^*$ diagrams within the tree level approximation, and find that the $\kappa$-meson exchange may contribute significantly to $K^*\Sigma$ photoproduction, while it is rather supplementary in $K^*\Lambda$ photoproduction. We demonstrate how the observables of $K^*$ photoproduction can be used to constrain the $\kappa$ meson properties. In particular, the parity asymmetry can separate the $\kappa$ meson contribution in $K^*$ photoproduction.