The decrease of light yield collection for scintillation counters of CDF muon trigger over time

The muon system of CDF spectrometer plays an important role in investigating processes with heavy quarks. The efficient functioning of scintillation counters, which comprise a considerable part of the CFD muon trigger, is a necessary condition for obtaining experimental data. The results of long-term measurements of the light yield, collected far from the photomultiplier end of the scintillation plate for different types of counters in order to predict the period of their effective operation in experiments, are presented.     

Scintillation counters of the muon system at CDF II

The framework of scintillation counters for the CDF II muon system at the Tevatron collider at Fermilab is described. Information from the detectors of the muon system is essential for forming triggers of the first and second levels and for an “off-line” data analysis related to studies in the field of the heavy quark physics, Standard Model tests, search for phenomena beyond its limits, and for many other CDF II experiments with p \(\bar p\) collisions at the energy √s = 1.96 TeV.     

New-generation large-area muon scintillation counters with wavelength shifter fiber readout for CDF II

New scintillation counters have been designed and constructed for upgrading the CDF detector at Fermilab Tevatron. A novel light collection technique using wavelength shifting fibers, together with a high-quality polystyrene-based scintillator UPS 923A, has resulted in compact counters with good and stable light collection efficiency over their lengths extending up to 320 cm. The design, construction, and performance of the counters are presented. Properties of the fibers and the scintillator, such as light output, light attenuation, decay time, and long-term stability, are investigated. It is found that the polystyrene-based scintillator, unlike the polyvinyltoluene-based one, has properties more adequate for long-term experiments. The text was submitted by the authors in English. On leave from NPL, Samarkand State University, Uzbekistan. On leave from HEPI, Tbilisi State University, Georgia.     

Possible modification of level 1 trigger of the CDF muon system at increased Tevatron luminosity

The increase in the Tevatron (FNAL) luminosity up to ≥ 2.0 × 10³² cm^?2 s^?1 and the level 1 (L1) trigger rate limitation resulted in tougher event selection conditions at CDF II; this led, in particular, to elimination from L1 muon trigger data from muon detectors in the pseudorapidity interval 1 < |η| < 1.25. A new muon trigger is proposed and investigated; this trigger includes signals from an additional layer of scintillation counters in the above η interval. The modified L1 muon trigger provides an acceptable for CDF II rate of lower than 1 kHz.     

Calibration of scintillation counters of the upgraded calorimeter of the IHEP-JINR Neutrino Detector for time of flight particle identification

In this paper, specific features of operation of the calorimeter of the IHEP-JINR Neutrino Detector on the basis of liquid scintillation counters upgraded for time of flight particle identification are described. Data acquisition system, algorithms of response reconstruction, and calibration of calorimeter counters are described in detail. Estimate of time and spatial resolution of counters is obtained on tracks of vertical cosmic muons. The averaged time resolution is σ = 1.2 ns, and the coordinate resolution is σ = 13 cm.     

New Generation of Large Scale Scintillation Counters for Detection of EAS and Use in Guard Systems of Experimental Physics Setups

The work is dedicated to the discussion of four new types of large-area scintillation counters design intended for detection of EAS and the use in the guard systems of experimental physics setups with low-cost production. The solid counters based on scintillating polystyrene plates are produced by melting clear polystyrene granules with additives in a mirror mold. Other counters are based on lentil-like polystyrene scintillation granules which are a new kind of plastic scintillators produced at IHEP. WLS fibers and SiPM as a photo sensor are used for a light detection. The dimensions of the tested detectors were 500 × 500 and to 1000 × 1000 mm2, their measured light output was up to 180 ph.e.     

Wigner-Matrix-Based Normality Test and Application to Weak Signal Detection in SISO/SIMO Systems

Based on the asymptotic spectral distribution of Wigner matrices,a new normality test method is proposed via reforming the white noise sequence.In this work,the asymptotic cumulative distribution function(CDF)of eigenvalues of the Wigner matrix is deduced.A numerical Kullback-Leibler divergence of the empirical spectral CDF based on test samples from the deduced asymptotic CDF is established,which is treated as the test statistic.For validating the superiority of our proposed normality test,we apply the method to weak 8PSK signal detection in the single-input single-output(SISO) system and the single-input multiple-output(SIMO)system.By comparing with other common normality tests and the existing signal detection methods,simulation results show that the proposed method is superior and robust.     

基于提升方案的CDF(1,5)整-整可逆双正交小波变换在渐进性无损图像压缩中的应用

讨论了基于双正交小波变换提升方案在图像压缩中的应用 ,研究了CDF( 1,3) ,CDF( 1,5 )双正交小波消失矩对图像压缩的影响。实验结果表明 ,在图像压缩中应尽可能选取具有较高消失矩的双正交小波 ,用CDF( 1,5 )双正交小波提升方案实现了基于整数运算的整 整可逆双正交小波变换 ,以及快速的、渐进性的直至无损图像压缩     

Status of the development of the imaging proportional counters for the Stellar X-Ray Polarimeter

Summary The Stellar X-Ray Polarimeter SXRP will be flown at the focus of the SODART X-ray telescope aboard the Russian satellite SPECTRUM-X-Gamma by the end of 1995. Four imaging proportional counters will detect photons diffracted by a graphite crystal (2.6 and 5.2 keV) and scattered from a lithium rod enclosed in a beryllium case (from 5 to 20 KeV). The counters are position-sensitive by the Wedge and Strip (WS) readout method. The gas mixture is 80% xenon, 10% argon and 10% methane. In this contribution we resume the results of the measurements performed on the engineering models of the counters. Position resolution of about 1.5 mm is attained with an energy resolution of about 25%. The pulse shape discrimination offers more than 98%⁶⁰Co events rejection, with at least 90% X-ray acceptance. Some improvements are foreseen for the flight units in terms of sensitivity and uniformity of response.     

Explaining Tevatron leptons photons missing-E T events with supersymmetry

The CDF experiment reported a lepton photon missing transverse energy (ie651_01)signal 3σ in excess of the standard model prediction in Tevatron Run I data. The excess can be explained by the resonant production of a smuon, which subsequently decays to a muon, a photon and a gravitino. Here, we perform combined fits of this model to the CDF (ie651_02) excess, the DO measurement of the same channel and the CDF (ie651_03) channel. Although the rates of the latter two analyses are in agreement with the standard model prediction, our model is in good agreement with these data because their signal to background efficiency is low at the best-fit point. However, they help to constrain the model away from the best fit point.     

Properties of the top quark

The top quark was discovered at the CDF and D0 experiments in 1995. As the partner of the bottom quark its properties within the Standard Model are fully defined. Only the mass is a free parameter. The measurement of the top quark mass and the verification of the expected properties have been an important topic of experimental top quark physics since. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarised. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties.     

Cosmic-ray calibration of lead scintillation monitor with internal trigger

Cosmic-ray calibration of the 4-channel lead scintillation monitor with internal trigger shows that the consideration of only coinciding signals of counters placed in the monitor depth and detecting the final part of the high-energy photon shower, with signals of any other counters at the monitor top, detecting both the initial part of the high-energy photon shower and low-energy background photons, decreases the number of detected coincidences by a factor of 2–4. An increase in the number of such coincidences when using the monitor in the setup for studying neutral pion photoproduction on nuclei in the photon beam of the labeling system of the “PAKHRA” accelerator of the Lebedev Physical Institute makes it possible to separate the high-energy electromagnetic shower from the low-energy background and to monitor the beam photon energy.     

Particle detectors for the future antiproton Paul trap of the ASACUSA experiment at CERN

Two detectors which will be used to commission a superconducting radiofrequency Paul trap for antiprotons, now being constructed at CERN and MPQ, are described. One is a microwire secondary electron emission monitor which will nondestructively measure the spatial profile of a low energy (E= 10?100 keV) antiproton beam. The other is a system of electromagnetic shower counters which will detect the secondary particles emerging from the antiproton annihilations occurring in the trap.     

二维提升的CDF(1,3)小波结合改进的SPIHT的渐进性无损图像压缩方法

针对传统小波变换计算复杂的缺点和多级树集合分裂算法(SPIHT)编码过程重复运算、存储量大的问题,提出了一种二维提升的CDF(1,3)小波结合改进的SPIHT的渐进性无损图像压缩方法。对整数CDF(1,3)双正交小波变换实现二维提升,利用提升的小波对图像做变换,提高了运算速度、便于硬件实现。对SPIHT算法加以改进,根据各个子图像的不同特点,改变扫描路线,采用四路并行分块处理的方法,提高了编码速度,降低了编解码过程的运算复杂度和时间消耗。利用提升的CDF(1,3)小波变换结合改进的SPIHT实现了渐进性无损图像压缩,证明了二维提升方案的有效性。     

Deterministic schedules for robust and reproducible non-uniform sampling in multidimensional NMR

We show that a simple, general, and easily reproducible method for generating non-uniform sampling (NUS) schedules preserves the benefits of random sampling, including inherently reduced sampling artifacts, while removing the pitfalls associated with choosing an arbitrary seed. Sampling schedules are generated from a discrete cumulative distribution function (CDF) that closely fits the continuous CDF of the desired probability density function. We compare random and deterministic sampling using a Gaussian probability density function applied to 2D HSQC spectra. Data are processed using the previously published method of Spectroscopy by Integration of Frequency and Time domain data (SIFT). NUS spectra from deterministic sampling schedules were found to be at least as good as those from random schedules at the SIFT critical sampling density, and significantly better at half that sampling density. The method can be applied to any probability density function and generalized to greater than two dimensions.     

Use of silica aerogels in Cherenkov counters

Silica aerogel is widely used as a radiator for Cherenkov detectors. It is a highly porous, low-density, and transparent substance with refractive index n ranging between the values of n < 1.001 for gaseous and n ≈ 1.3 for condensed phases. The review is devoted to the consideration of various factors affecting the identification of particles in Cherenkov counters: the chromatic aberration, the number of photoelectrons, and the optical-system light transmittance. A brief review is given for principal methods of aerogel production, its manufacturers, optical and physical characteristics of aerogel samples, their transparency, scattering and absorption lengths, and number of photoelectrons. The use of silica aerogels in various threshold Cherenkov counters at such installations as BELLE (KEK), TASSO (DESY), and KEDR (VEPP-4M) is considered. In recent years, many research works have been carried out at the CERN proton synchrotron using various prototypes of Cherenkov counters. This review considers some of them. The progress achieved in manufacturing high-quality aerogel samples including the multilayer ones and the results of the tests were beneficial for implementing these materials in the Ring-imaging Cherenkov (RICH) counters at HERMES, developing the proximity focusing RICH detectors, and for proposing RICH detectors for the LHCb project at the CERN ring collider and at the Alpha Magnetic Spectrometer on the International Space Station.     

Thin-film breakdown counters and their applications (review)

Experimental techniques based on the use of thin-film breakdown counters fabricated at Khlopin Radium Institute are reviewed.     

Studying the characteristics of scintillation counters in a beam of relativistic particles

In this work, the results of the measurements of characteristics of 40-cm and 2-m scintillation counters irradiated by a particle beam with a momentum of 7 GeV/c from the accelerator of the Institute for High Energy Physics are presented. The scintillators used in counters are BC-404 and BC-408 scintillators. The counters are viewed from both ends by R1828-01 photomultiplier tubes. The PMT signal spectra are well described by a convolution of the Landau and Gaussian distributions. Their width is determined mainly by fluctuations of ionization energy losses. The time distributions of the signals obey the Gaussian law. For the 40-cm counter, the time resolution is σ(T) = 88 ps; for the 2-m counter, it varies from 120–160 ps in its center to ~100 ps near the end.     

The 90 ton liquid scintillation detector in the Mont Blanc laboratory

Summary We discuss here the results from calibrating liquid seintillation counters (1.5 m³ each) used in the large-volume neutrino experiment in the Mont Blanc Laboratory. The electronic and recording systems from the 72 counters of the detector are described, and the method to detect low-energy γ pulse from (n, p) reaction by using²⁵²Cf as a neutron source is discussed. Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.