119255652
Bucking coil implementation on PMT for active canceling of magnetic field
Aerogel and water Cerenkov detectors were employed to tag kaons for a lambda hypernuclear spectroscopic experiment which used the (e,e'K{sup +}) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ~5 Gauss at the photomultiplier tubes (PMT) for these detectors which could not be easily shielded. As this field results in a lowered kaon detection efficiency, we implemented a bucking coil on each photomultiplier tubes to actively cancel this magnetic field, thus maximizing kaon detection efficiency.
123404629
Position reconstruction in fission fragment detection using the low pressure MWPC technique for the JLab experiment E02-017
When a Lambda hyperon is embedded in a nucleus it can form a hypernucleus. The lifetime and its mass dependence of stable hypernuclei provide information about the Lambda N interaction in the nuclear medium. This work will introduce the Jefferson Lab experiment (E02-017), which aims to study the lifetime of the heavy hypernuclei using a specially developed fission fragment detection technique: a multi-wire proportional chamber operating under low gas pressure (LPMWPC). The trajectory of the detected fragment is reconstructed and used to find the fission point on the target foil, the position resolution is less than 1 mm, which meets the original design, the separation of target materials and events mixture percentage in different regions are verified by Monte Carlo simulation.
117483375
Sigma hyperons in the nucleus
A search for {sigma} hypernuclear states in p -shell hypernuclei has been performed with the Moby Dick spectrometer and the low energy separated beam (LESB-2) at the Brookhaven Alternating Gradient Synchrotron (BNL AGS). Unlike some previously published reports, no narrow states have been observed for targets of {sup 6}Li and {sup 9}Be in (K{sup -}, {pi}{sup {+-}}) reactions, either for bound state or continuum regions. Together with the previously reported J=0 , T=1/2 bound state in {sup 4}{sub {sigma}} He , these results demonstrate the crucial role of isospin in {sigma} hypernuclei. (c) 1999 The American Physical Society.
118050037
MEGA : A Search for the rare decay mu —g e gamma at the level of 5 x 10**-13
122783059
Radio frequency picosecond phototube
Abstract We propose a photon detector for recording low-level and ultra-fast optical signals, based on radio frequency (RF) analysis of low-energy photoelectrons (PEs). By using currently developed 500 MHz RF deflector, it is possible to scan circularly and detect single PEs, amplified in multi-channel plates (MCPs). The operation of the tube is investigated by means of thermionic electron source. It is demonstrated that the signals generated in the MCP can be processed event by event; by using available nanosecond electronics and that time resolution better than 20 ps can be achieved. Timing characteristics of the Cherenkov detector with RF phototube in a ‘head-on’ geometry is investigated by means of Monte Carlo simulation.
123272214
New (e,e′K+) hypernuclear spectroscopy with a high resolution kaon spectrometer
Abstract A new ( e , e ′ K + ) hypernuclear spectroscopy is proposed at Jefferson Lab. With a newly designed high resolution kaon spectrometer (HKS) and a new experimental configuration to reduce background electrons associated with bremsstrahlung, it is expected to realize much higher yield and hypernuclear mass resolution than those of the first successful experiment at Jefferson Lab Hall-C, which demonstrated the feasibility of hypernuclear electroproduction for Λ hypernuclear spectroscopy.
119236104
Fermion correction to the mass of the scalar glueball in QCD sum rule
Contributions of fermions to the mass of the scalar glueball $0^{++}$ are calculated at two-loop level in the framework of QCD sum rules. It obviously changes the coefficients in the operator product expansion (OPE) and shifts the mass of glueball.
119227533
Molecular states with hidden charm and strange in QCD Sum Rules
This work uses the QCD Sum Rules to study the masses of the and molecular states with quantum numbers . Interpolating currents with definite C-parity are employed, and the contributions up to dimension eight in the Operator Product Expansion (OPE) are taken into account. The results indicate that two hidden strange charmonium-like states may exist in the energy ranges of and , respectively. The hidden strange charmonium-like states predicted in this work may be accessible in future experiments, e.g., BESIII, BelleII and SuperB. Possible decay modes, which may be useful in further research, are predicted.