198186499
THE PROGRESS OF BEPCII STORAGE RING DIAGNOSTICS SYSTEM
In this paper, we will present the progress of BEPCII storage rings beam diagnostics system along with the BEPCII commissioning. Tools such as Libera BPM had been used for the BPR first turn measurement and the injection residual orbit research of BER. COD_BPM can satisfy the resolution requirement for the beam-beam scan in the interaction region, and for the COD measurement, BCM (bunch current monitor) can help us on the different injection pattern. The TFB system is important to suppress the strong multi-bunch instabilities during the higher beam current running. The tune meters, the beamloss monitors, DCCT and SLM (synchrotron light monitor) are also described in this paper.
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.
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.
201926003
THE BEPCII DCCT SYSTEM
A DC Current Transformer (DCCT) as a standard diagnostic system for beam current plays an important role in BEPCII, the upgrade project of the Beijing Electron Positron Collider. Two DCCTs are operating now, separately in the electron and positron rings, to monitor the beam current, the beam injection rate, the beam loss rate and the beam lifetime. In this paper, the mechanical structure design, readout system and data processing are presented. The progress of DCCTs on each step of BEPCII commissioning, such as improving the beam lifetime and reducing the background noise, are also included.
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.
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.
13628240
Light-cone QCD predictions for elastic ed scattering in the intermediate energy region
The contributions of helicity-flip matrix elements to the deuteron form factors are discussed in the light-cone frame. Normalized A(Q(2)), B(Q(2)), G(Q)(Q(2)), and T-20 are obtained in a simple QCD-inspired model. As a result of the kinematical enhancement, the helicity-flip matrix elements contribute significantly to G(M) and G(Q) while eta is small. Our numerical results are consistent with data in the intermediate energy region.
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.
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.
242130
Daya Bay Neutrino Experiment
The Daya Bay Neutrino Experiment is proposed to measure sin(2) 2 theta(13) to better than 0.01 at 90% C.L. in a three-year run. The experimental site, detector design, and background estimation are presented.