119501195
A Phenomenological expression for deuteron electromagnetic form-factors based on perturbative QCD predictions
For deuteron's electromagnetic form factors, perturbative QCD (pQCD) predicts that G(00)(+) becomes the dominate helicity amplitude and G(+0)(+), and G(+-)(+) are suppressed by factors Lambda QCD/Q and Lambda (2)(QCD)/Q(2) at large Q(2) respectively. We try to discuss the higher-order corrections beyond the pQCD asymptotic predictions by interpolating an analytical form to the intermediate energy region. From fitting the data, our results show that the helicity-zero to zero matrix element G(00)(+) dominates the gross structure function A(Q(2)) in both the large and intermediate energy regions. It is a good approximation for G(+-)(+) to ignore the higher-order contributions and the higher-order corrections to G(+0)(+) should be taken into account due to sizeable contributions in the intermediate energy region.
15989714
Deuteron electromagnetic form factors in the intermediate energy region.
Based on a perturbative QCD analysis of the deuteron form factor, a model for the reduced form factor is suggested. The numerical result is consistent with the data in the intermediate energy region. {copyright} {ital 1996 The American Physical Society.}
121084890
Detection methods at reactor neutrino experiments
Abstract In 2011 and 2012, the smallest neutrino mixing angle θ 13 was determined to be unexpected large by reactor neutrino experiments Daya Bay, Double Chooz, and RENO, and accelerator experiments T2K and MINOS. The most precise measurement is sin 2 2 θ 13 = 0.089 ± 0.010 ( stat . ) ± 0.005 ( syst . ) , provided by Daya Bay. The measurement of θ 13 opened the gateway to the mass hierarchy and CP phase measurements. It also marked the beginning of precision measurements in neutrino studies. With near-far relative measurement and improvements in detector design, the relative precision of neutrino detectors reached 0.2%. Detection methods for reactor neutrinos are reviewed. The highlighted techniques include gadolinium-doped liquid scintillator, three-layer detectors, functionally identical detectors, reflective panel, background shielding, etc. The next generation reactor neutrino experiment Daya Bay II and its technical challenges are briefly described.
55221705
Measurement of decay time of liquid scintillator
In this paper we describe a single photon method to measure the decay time of two kinds of homemade liquid scintillator. We find that the fast and slow decay time constants of these two samples, with 5cm diameter and 4cm height, are about similar to 4ns and similar to 17ns, respectively. These results are checked through a reference measurement by recording the scintillation pulse shapes at the output of a fast response PMT directly by a digital oscilloscope. The time responses of these two samples are as good as those of commercial liquid scintillator. (C) 2008 Elsevier B.V. All rights reserved.
125502899
Daya Bay reactor neutrino experiment
55451255
Determining Reactor Neutrino Flux
Abstract Flux is an important source of uncertainties for a reactor neutrino experiment. It is determined from thermal power measurements, reactor core simulation, and knowledge of neutrino spectra of fuel isotopes. Past reactor neutrino experiments have determined the flux to (2–3)% precision. Precision measurements of mixing angle θ 13 by reactor neutrino experiments in the coming years will use near-far detector configurations. Most uncertainties from reactor will be canceled out. Understanding of the correlation of uncertainties is required for θ 13 experiments. Precise determination of reactor neutrino flux will also improve the sensitivity of the non-proliferation monitoring and future reactor experiments. We will discuss the flux calculation and recent progresses.
173169030
WIRE SCANNER FOR TRANSVERSE BEAM PARAMETER MEASURE- MENT IN BEPCII
BEPCII, the upgrade project of Beijing Electron Positron Collider (BEPC), is an accelerator with large beam current and high luminosity, so an efficient and stable injector is required. Several beam diagnostic and monitoring instruments are used. A new diagnostic instrument wire scanner, has been designed and will be used to measure the profile of the linac beam of BEPCII. This paper describes the prototype of this system and the cause of heat generating of the wire. Some simulation results of the heat and force by using finite element method softwareANSYS, are presented and discussed.
22957262
DAQ System of BPM and BCT for the BEPCII Linac
Following the BEPCII upgrade, total about 19 BPMs and 12 BCTs have been newly installed in the BEPCII Linac. Also, a set of distributed control system based on EPICS architecture has been built, and the BPM and BCT system are merged into the new control system for the data acquisition. In order to reduce the effects of RF noise, a special gated integrator was used for the BCT system. In this paper we will describe the DAQ system of BPM and BCT including calibrations in detail.
54677120
BEPC BEAM INSTRUMENTATION SYSTEM AND ITS UPGRADE FOR BEPC-II
The Beijing Electron Positron Collider (BEPC) has been successfully operated for many years since 1989. Now BEPC is proposed to upgrade to BEPC-II. The beam instrumentation system of the BEPC storage ring includes many subsystems such as BPMs, tune measurement, current monitor, synchrotron radiation monitor, etc. This paper will describe the present operation performance of the beam instrumentation system of the BEPC storage ring and its upgrade plan for BEPC-II.
40534119
Synchrotron radiation monitoring system at BEPC
The synchrotron radiation by the relativistic particles is a useful and important diagnostic tool to obtain various beam parameters. The visible light of the synchrotron radiation emitted in a bending magnet of the BEPC storage ring is reflected through the window by a water-cooled mirror in the vacuum chamber and then directed by a remote controlled mirror onto the optical bench supporting the diagnostic instruments in the dark room. These instruments include a CCD camera providing the image of the beam transverse profile on a TV monitor, a lens system focusing the synchrotron light onto a solid state scanned photodiode arrays to obtain the beam height or width, a streak camera to measure the bunch length for a single pass, and a two-dimensional position sensing photo-detector to monitoring the drift of the beam position. This paper gives the detailed description of the synchrotron radiation monitoring system at BEPC.
110785343
BEPC STORAGE RING BEAM LOSS MONITOR SYSTEM DESIGN
The Beijing Electron Positron Collider (BEPC) is a large experimental equipment for high energy physics as well as synchrotron radiation research in parasitic or dedicated mode. The beam loss phenomenon is frequently observed in the BEPC storage ring, especially when BEPC operates in the dedicated synchrotron radiation mode. Although the accelerator physics group has carried out some studies on this phenomenon, but so far this phenomenon has not well explained. The beam loss monitors (BLMs) have been developed for detecting and locating any possible excessive beam loss with the injection process, beam instabilities, bad vacuum, ion trapping, etc. This paper will discuss the system design considerations such as the detector-type selection, the BLM location in the ring and related experiment results, and so on.