18893994
The mass production and quality control of RPCs for the Daya Bay experiment
Abstract Resistive plate chambers will be used in the Daya Bay reactor neutrino experiment to help veto backgrounds created by cosmic-ray muons. The mass production of RPCs began in 2008 and by the end of 2009, 1600 RPCs (3500 m 2 ) had been produced and tested. This paper describes the production and quality control procedures, and quality assurance using cosmic-ray testing.
54915871
Improvement of main drift chamber Monte-Carlo tuning model at BESIII
Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the difference between simulation and data in track reconstruction efficiency reduces from 1% to 0.5% averagely for the pion in J/psi ->pi(+)pi(-)pi(0), and the momentum resolution agreement improves significantly for the proton in J/psi -> p (p) over bar.
17248811
A new surface treatment for the prototype RPCs of the BESIII spectrometer
The prototype resistive plate chambers (RPCs) for the BESIII spectrometer were constructed by using resistive electrodes made from a special type of phenolic paper laminates developed by us. The surface quality of these laminates is superior to other bakelite plates that have been used to construct RPCs elsewhere. A method for adjusting the resistivety of these laminates was also developed. Extensive studies were conducted by using a number of prototype RPCs in the last several years. Tests have shown prototype RPCs made by using our resistive plates without the linseed oil treatment can achieve the level of performance comparable to RPCs with linseed oil treated bakelite or resistive glass electrodes. In this paper, we will discuss the construction of these prototype RPCs. The test results of a prototype RPC that have been monitored for a year will be reported. Based on favorable test results of prototypes, the RPC production for the muon identifier of the BESIII spectrometer has started at the Beijing Gaonengkedi Science and Technology Co. Ltd. in early 2004 using the technology that we developed.
120491717
Measurement of radiation dose at the north interaction point of BEPC II
The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI(Tl) detector.
122140821
Primary vertex reconstruction based on the Kalman filter technique at BESIII
Primary vertex reconstruction is crucial to estimate the beam profile in collision experiments. We study the principle of an iterative process, called the Kalman filter method, and apply it to primary vertex reconstruction at BESIII. A Newton procedure to find the zero point of the distance function's gradient is used for primary vertex finding in 3-dimensional space. Results are obtained based on raw data at BESIII.
120261584
Overveiw of the BES physics
Recent physics results at Beijing Electron-Positron Collider (BEPC) are reviewed, especially on excited baryons. Substantial improvements are expected at the newly built BESIII experiment, which is operational since 2008. The detector performance is excellent and a total of 100 million Ψ(2S) and 200 million J/Ψ event are collected in 2009. Preliminary results shows that a new era of excited baryon physics will begin.
110608938
Production of long-strip multi-gap resistive plate chamber module for the STAR-MTD system
A new Long-strip Multi-gap Resistive Plate Chamber (LMRPC) prototype with 5 gas gaps has been developed for the Muon Telescope Detector (MTD) of the STAR experiment at RHIC in order to reduce the working High Voltage (HV) of previous design. Technical specifications related to the final infrastructure present in the experiment have motivated this effort. Its performance has been measured with cosmic rays. The efficiency of this prototype can reach 98% and the time resolution is around 95 ps. It shows a good uniformity among strips. The noise level is less than 0.2 Hz/cm2. The signal transmission and crosstalk of the modules was measured with a vector network analyzer, showing a good match with simulations within the amplifier bandwidth. A new cosmic-ray test system with long scintillators has been developed to accelerate the Quality Control (QC) process during the mass production of STAR-MTD. A selection of perpendicular cosmic-ray events for more accurate evaluation of the time resolution is achieved. The time resolution with this method is better, albeit with larger error, than the result obtained without any selection. A new spacer is used, resulting in a much reduced streamer ratio at comparable fields. Thirty-two modules have been built with the new spacer by the middle of April of 2012. They have been tested and they all have passed the QC.
118459115
Quasi-Single Field Inflation with Large Mass
We study the effect of massive isocurvaton on density perturbations in quasi-single field inflation models, when the mass of the isocurvaton M becomes larger than the order of the Hubble parameter H. We analytically compute the correction to the power spectrum, leading order in coupling but exact for all values of mass. This verifies the previous numerical results for the range 0 < M < 3H/2 and shows that, in the large mass limit, the correction is of order H2/M2.
119938939
Progress of R&D and production of timing RPCs in Tsinghua University
Abstract Multi-gap resistive plate chamber (MRPC) is a new kind of gas detector. It has good time resolution and high efficiency and has been adopted to construct the full barrel time-of-flight (TOF) detector for the STAR experiment at RHIC. The high rate TOF of CBM is also proposed to be assembled with MRPCs. Tsinghua University is a collaboration member of the two experiments and has made substantial progress on the R&D and production of MRPC. In this paper, we describe the development of low-resistivity glass and high rate MRPC, and the development of 1 m long counter is also described.
119276209
Planck priors for dark energy surveys
Although cosmic microwave background anisotropy data alone cannot constrain simultaneously the spatial curvature and the equation of state of dark energy, CMB data provide a valuable addition to other experimental results. However computing a full CMB power spectrum with a Boltzmann code is quite slow; for instance if we want to work with many dark energy and/or modified gravity models, or would like to optimize experiments where many different configurations need to be tested, it is possible to adopt a quicker and more efficient approach. In this paper we consider the compression of the projected Planck cosmic microwave background data into four parameters, R (scaled distance to last scattering surface), l{sub a} (angular scale of sound horizon at last scattering), {omega}{sub b}h{sup 2} (baryon density fraction) and n{sub s} (powerlaw index of primordial matter power spectrum), all of which can be computed quickly. We show that, although this compression loses information compared to the full likelihood, such information loss becomes negligible when more data is added. We also demonstrate that the method can be used for canonical scalar-field dark energy independently of the parametrization of the equation of state, and discuss how this method should be used for other kindsmore » of dark energy models.« less
6716887
Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collisions.
We report the first three-particle coincidence measurement in pseudorapidity (Δη) between a high transverse momentum (p⊥) trigger particle and two lower p⊥ associated particles within azimuth |Δϕ|<0.7 in square root of s(NN)=200 GeV d+Au and Au+Au collisions. Charge ordering properties are exploited to separate the jetlike component and the ridge (long range Δη correlation). The results indicate that the correlation of ridge particles are uniform not only with respect to the trigger particle but also between themselves event by event in our measured Δη. In addition, the production of the ridge appears to be uncorrelated to the presence of the narrow jetlike component.