238 Matching Results

Search Results

Advanced search parameters have been applied.

The RICH detector of the SELEX experiment

Description: A RICH detector was used during the 1996/7 Fixed Target run at Fermilab in experiment E781 - SELEX. The detector utilizes a matrix of 2848 phototubes for the photocathode. The Figure of Merit, N{sub 0}, has been measured to be in excess of 100 cm{sup -1}. The ring radius resolution for multitrack events has been measured to be 1.8 mm, which gives K/{pi} separation on a 2{sigma} level up to a momentum of 165 GeV/c, and p{pi} separation up to 320 GeV/c. We will describe the design of the detector, discuss the stability during operation, and report on achieved results.
Date: December 1, 1998
Creator: J.Engelfried, I.Filimonov, J.Kilmer, A.Kozhevnikov, V.Kubarovsky, V.Molchanov, A.Nemitkin, E.Ramberg, V.Rud and L.Stutte
Partner: UNT Libraries Government Documents Department

A Liquid-Hydrogen Cerenkov Counter

Description: Two models of a liquid-hydrogen (?-illegible) Cherenkov counter (illegible) been constructed (illegible). The first served as a prototype (?-illegible) and was (illegible) to demonstrate the feasibility (?-illegible) of the (illegible) concept (?-illegible) (illegible) liquid hydrogen does not give scintillation (?-illegible) (illegible) that of Cherenkov light. The second, final version (?-illegible), (illegible) in an experiment (?-illegible) in which particles brought to rest (?-illegible) (illegible) (illegible) electrons. In this second counter, the efficiency (?-illegible) (illegible) relativistic (?-illegible) particles (?-illegible) by their Cherenkov radiation in liquid hydrogen (?-illegible) was measured by stopping (illegible) mesons in the hydrogen and detecting their decay electrons outside (?-illegible) of the flask (?-illegible) after a suitable time delay. An average detection (?-illegible) efficiency (?-illegible) of 75% (?-illegible) was (illegible) taken over the volume of the hydrogen (?-illegible).
Date: May 9, 1963
Creator: Zipi, T.F.; Chamberlain, Owen; Kadyk, John A. & York, Carl M.
Partner: UNT Libraries Government Documents Department

Fast Electronics in High-Energy Physics

Description: A brief review of fast electronics is given, leading up to the present state of the art. Cherenkov counters in high-energy physics are discussed, including an example of a velocity-selecting Cherenkov counter. An electronic device to aid in aligning external beams from high-energy accelerators is described. A scintillation-counter matrix to identify bubble chamber tracks is discussed. Some remarks on the future development of electronics in high-energy physics experiments are included.
Date: August 8, 1958
Creator: Weigand, Clyde
Partner: UNT Libraries Government Documents Department

The E781 (SELEX) RICH detector

Description: First results from a new RICH detector, operating in an experiment currently taking data - Fermilab E781 (SELEX), are presented. The detector utilizes a matrix of 2848 phototubes for the photocathode. In a 650 GeV/c ?r- beam the number of photons detected is 14 per ring, giving a Figure of Merit No of 106 cm-`. The ring radius resolution obtained is 1.2 %. Results showing the particle identification ability of the detector are discussed.
Date: June 1, 1997
Creator: Engelfried, J.
Partner: UNT Libraries Government Documents Department

Observing muon decays in water Cherenkov detectors at the Pierre Auger Observatory

Description: Muons decaying in the water volume of a Cherenkov detector of the Pierre Auger Observatory provide a useful calibration point at low energy. Using the digitized waveform continuously recorded by the electronics of each tank, we have devised a simple method to extract the charge spectrum of the Michel electrons, whose typical signal is about 1/8 of a crossing vertical muon. This procedure, moreover, allows continuous monitoring of the detector operation and of its water level. We have checked the procedure with high statistics on a test tank at the Observatory base and applied with success on the whole array.
Date: August 1, 2005
Creator: Allison, P.; Arneodo, F.; Bertou, Xavier; Busca, N.; Ghia, P.L.; Medina, C. et al.
Partner: UNT Libraries Government Documents Department

Study of wavelength-shifting chemicals for use in large-scale water Cherenkov detectors

Description: Cherenkov detectors employ various methods to maximize light collection at the photomultiplier tubes (PMTs). These generally involve the use of highly reflective materials lining the interior of the detector, reflective materials around the PMTs, or wavelength-shifting sheets around the PMTs. Recently, the use of water-soluble wavelength-shifters has been explored to increase the measurable light yield of Cherenkov radiation in water. These wave-shifting chemicals are capable of absorbing light in the ultravoilet and re-emitting the light in a range detectable by PMTs. Using a 250 L water Cherenkov detector, we have characterized the increase in light yield from three compounds in water: 4-Methylumbelliferone, Carbostyril-124, and Amino-G Salt. We report the gain in PMT response at a concentration of 1 ppm as: 1.88 {+-} 0.02 for 4-Methylumbelliferone, stable to within 0.5% over 50 days, 1.37 {+-} 0.03 for Carbostyril-124, and 1.20 {+-} 0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modeled, resulting in a simulated gain within 9% of the experimental gain at 1 ppm concentration. Finally, we report an increase in neutron detection performance of a large-scale (3.5 kL) gadolinium-doped water Cherenkov detector at a 4-Methylumbelliferone concentration of 1 ppm.
Date: September 21, 2011
Creator: Sweany, M; Bernstein, A; Dazeley, S; Dunmore, J; Felde, J; Svoboda, R et al.
Partner: UNT Libraries Government Documents Department


Description: The scintillation and Cherenkov properties of UVA (ultraviolet absorbing) and UVT (ultraviolet transmitting) Plexiglas specimens were tested by analyzing cosmic-rayinduced pulses traversing the materials. It was found that the UVT sample has less than 1/6 the scintillation effect of UVA and is preferred for use in counters. (J.R.D.)
Date: September 1, 1960
Creator: Balzarini, D.
Partner: UNT Libraries Government Documents Department

Photon detectors with gaseous amplification

Description: Gaseous photon detectors, including very large 4{pi}-devices such as those incorporated in SLD and DELPHI, are finally delivering physics after many years of hard work. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photoelectrons. Among detector builders, there is hardly anybody who did not make mistakes in this area, and who does not have a healthy respect for the problems involved. This point is stressed in this paper, and it is suggested that only a very small operating phase space is available for running gaseous photon detectors in a very large system with good efficiency and few problems. In this paper the authors discuss what was done correctly or incorrectly in first generation photon detectors, and what would be their recommendations for second generation detectors. 56 refs., 11 figs.
Date: August 1, 1996
Creator: Va`vra, J.
Partner: UNT Libraries Government Documents Department

Continued study of the time stability of a small water Cerenkov detector

Description: This note describes continued studies at Fermilab of the long term stability of a small water Cerenkov tank. Previous results are presented for studies between November, 1997 and October, 1998. The data given here continue these measurements through December, 1998, when the tank and electronics were moved to a different location, and then to November, 1999. The water tank, bag liner, water, photomultiplier tube, and data acquisition software were unchanged for the additional measurements from June to November, 1999. However, some details of the geometry of the trigger counters relative to the tank and of the electronics may have differed. The setup for the 1999 results is described in this note. The same analog-to-digital converter (ADC) was used for both time periods. Its pedestal was quite stable during the 1997--1998 measurements, but sizeable changes were observed in the more recent runs. As a result, dedicated pedestal runs were performed, and a number of additional tests were conducted.
Date: April 3, 2000
Creator: Strom, D.; Glass, H.; Spinka, H. & Thomure, M.
Partner: UNT Libraries Government Documents Department

The CO2 Gas Cherenkov Detectors for the Jefferson Lab Hall A Spectrometers

Description: Two threshold gas Cherenkov counters have been constructed for the electron and hadron High Resolution Spectrometers (HRS) of the Jefferson Lab Experimental Hall A. These counters are intended to separate electrons/positrons from other particles up to 4 GeV/c. The counters are operated at atmospheric pressure with CO2. Each counter is equipped with ten mirrors. Lightweight, thin, spherical mirrors (5.5 + 10{sup {minus}3} radiation lengths) have been employed resulting in a total thickness of 1.4 + 10{sup {minus}2} radiation lengths crossed by the particles. A prototype of the counter has been tested at CERN with a mixed beam of positrons, pions, and protons from 1 to 4 GeV/c. Its detection efficiency for positrons and the rejection ratios for pions and protons have been measured as a function of the pulse height response (or equivalently the number of photoelectrons). An improvement of 34% in the number of photoelectrons has been obtained by using a wavelength shifter coated on the photocathode glass window. With such an improvement in 1 m long radiator, an inefficiency for positrons less than 10{sup {minus}3} and rejection ratios pi/e at the level of few 10{sup {minus}3} and p/e smaller than 10{sup {minus}3} have been obtained for pulse heights above 2 photoelectrons. Contaminations of particles below the Cherenkov threshold is fully understood considering delta-rays production.
Date: June 1, 1998
Creator: Iodice, M.; Cisbani, E.; Colilli, S.; Crateri, R.; Frullani, S.; Garibaldi, F. et al.
Partner: UNT Libraries Government Documents Department

Neutrino properties and fundamental symmetries

Description: This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). There are two components to this work. The first is a development of a new detection scheme for neutrinos. The observed deficit of neutrinos from the Sun may be due to either a lack of understanding of physical processes in the Sun or may be due to neutrinos oscillating from one type to another during their transit from the Sun to the Earth. The Sudbury Neutrino Observatory (SNO) is designed to use a water Cerenkov detector employing one thousand tonnes of heavy water to resolve this question. The ability to distinguish muon and tau neutrinos from electron neutrinos is crucial in order to carry out a model-independent test of neutrino oscillations. We describe a developmental exploration of a novel technique to do this using {sup 3}He proportional counters. Such a method offers considerable advantages over the initially proposed method of using Cerenkov light from capture on NaCl in the SNO. The second component of this work is an exploration of optimal detector geometry for a time-reversal invariance experiment. The question of why time moves only in the forward direction is one of the most puzzling problems in modern physics. We know from particle physics measurements of the decay of kaons that there is a charge-parity symmetry that is violated in nature, implying time-reversal invariance violation. Yet, we do not understand the origin of the violation of this symmetry. To promote such an understanding, we are developing concepts and prototype apparatus for a new, highly sensitive technique to search for time-reversal-invariance violation in the beta decay of the free neutron. The optimized detector geometry is seven times more sensitive than that in previous experiments. 15 refs.
Date: July 1, 1996
Creator: Bowles, T.J.
Partner: UNT Libraries Government Documents Department

DIRC Dreams: Research Directions for the Next Generation of Internally Reflected Imaging Counters

Description: Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.
Date: August 17, 1999
Creator: Ratcliff, Blair N
Partner: UNT Libraries Government Documents Department


Description: The US Long Baseline Neutrino Experiment Study was commissioned jointly by Brookhaven National Laboratory (BNL)and Fermi National Accelerator Laboratory (FNAL) to investigate the potential for future U.S. based long baseline neutrino oscillation experiments using MW class conventional neutrino beams that can be produced at FNAL. The experimental baselines are based on two possible detector locations: (1) off-axis to the existing FNAL NuMI beamline at baselines of 700 to 810 km and (2) NSF's proposed future Deep Underground Science and Engineering Laboratory (DUSEL) at baselines greater than 1000km. Two detector technologies are considered: a megaton class Water Cherenkov detector deployed deep underground at a DUSEL site, or a 100kT Liquid Argon Time-Projection Chamber (TPC) deployed on the surface at any of the proposed sites. The physics sensitivities of the proposed experiments are summarized. We find that conventional horn focused wide-band neutrino beam options from FNAL aimed at a massive detector with a baseline of > 1000km have the best sensitivity to CP violation and the neutrino mass hierarchy for values of the mixing angle {theta}{sub 13} down to 2{sup o}.
Date: August 6, 2007
Creator: BISHAI,M.
Partner: UNT Libraries Government Documents Department

Ion Feedback Suppression Using Inclined MCP Holes in a _Single-MCP+Micromegas+Pads_ Detector

Description: We show that the ion backflow to photocathode can be completely suppressed if one uses inclined MCP holes in a presence of magnetic field. The inclined hole angles are chosen to be aligned with the Lorentz electron angle allowing the electron transmission and amplification, while positive ions, traveling along a different angle, are caught on the MCP hole walls. The detector under investigation is a new gaseous detector structure based on a tandem of two parts, a single MCP (Microchannel) plate, a Micromegas with pad readout. We are aiming to develop a gaseous photon detector with the Bialkali photocathode, however, one could use some ideas in the paper for other types of detectors.
Date: September 30, 2005
Creator: Va'vra, J.; /SLAC; Sumiyoshi, T. & U., /Tokyo Metropolitan
Partner: UNT Libraries Government Documents Department

Development of Photon Detectors for a Fast Focusing DIRC

Description: We report progress in developing a Focusing DIRC with very good timing resolution. This basic detector development has been motivated by a possible upgrade of the very successful BaBar DIRC particle identification detector for a future Super B-factory. We have built a single bar full size prototype, which aims to reduce the chromatic error by precise timing, and to remove the effect of bar thickness with a focusing mirror. This paper describes the design of the prototype, and systematic studies of the timing resolution and position response for single photons for two 64-pixel detectors: (a) Hamamatsu Flat Panel PMTs, and (b) Burle MCP-PMTs. To test the prototype, we have developed new electronics for {approx}300 pixels capable of measuring a single electron timing resolution to {approx}100ps. We also report on a first measurement of aging with the MCP-PMT.
Date: September 30, 2005
Creator: Field, C.; Hadig, T.; Leith, David W.G.S.; Mazaheri, G.; Ratcliff, B.; Schwiening, J. et al.
Partner: UNT Libraries Government Documents Department

Radial tail resolution in the SELEX RICH

Description: The authors use a 7 Million event data sample of 600 GeV/c single track pion events, where the pion track is reconstructed upstream and downstream of the SELEX RICH. They build the RICH ring radius histogram distribution and count the tail events that fall outside 5{sigma}, giving a fraction of 4 x 10{sup -5} events outside the Gaussian tails. This control of events establishes the ability of using the RICH as velocity spectrometer for high precision searches of the K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}} decay like it is planned in the CKM experiment.
Date: January 1, 2005
Creator: Morelos, A.; Mata, J.; Cooper, P. S.; Engelfried, J. & Aguilera-Servin, J. L.
Partner: UNT Libraries Government Documents Department

Can TMAE photocathode be used for high rate applications?

Description: The paper explores the problems associated with wire aging, charging effects and self-sustaining cathode currents in the TMAE based photo-detectors. It is generally believed that anode wire aging is the most serious problem encountered in TMAE (tetrakis dimethylamino ethylene)-based Cherenkov ring imaging detectors. Although charging effects and self-sustaining cathod currents have not been studied systematically, there is concern that they too could become significant over a long period of time.
Date: March 1, 1995
Creator: Va`vra, J.
Partner: UNT Libraries Government Documents Department

Fudge: a high-bandwidth fusion diagnostic of the NIF

Description: Diagnostics for the National Ignition Facility (NIF)/Inertial Confinement Fusion (ICF) program must include good characterization of the fusion source. Ideally, diagnostics would measure the spatially-resolved history of the fusion reaction rate and temperature. Existing diagnostics can satisfy this goal only partially. One class of new techniques that could play a major role in high-yield diagnostics is measurements based on fusion {gamma} rays. The Fusion Diagnostic Gamma Experiment (FUDGE) can be used to perform energy-resolved measurements of (D,T) fusion reaction rates This diagnostic is based on the 16 7-MeV {gamma} rays that are produced by (D,T) fusion. The {gamma} rays are free of spectral dispersion and can be detected with a high bandwidth Cherenkov detector. A simple magnetic monochromator selects signals from the 16 7-MeV {gamma} rays and reduces background signals from non-fusion {gamma} rays.
Date: June 2, 1998
Creator: Moran, M. J., LLNL
Partner: UNT Libraries Government Documents Department

A CMOS Integrating Amplifier for the PHENIX Ring Imaging Cherenkov detector

Description: A CMOS integrating amplifier has been developed for use in the PHENIX Ring Imaging Cherenkov (RICH) detector. The amplifier, consisting of a charge-integrating amplifier followed by a variable gain amplifier (VGA), is an element of a photon measurement system comprising a photomultiplier tube, a wideband, gain of 10 amplifier, the integrating amplifier, and an analog memory followed by an ADC and double correlated sampling implemented in software. The integrating amplifier is designed for a nominal full scale input of 160 pC with a gain of 20 mV/pC and a dynamic range of 1000:1. The VGA is used for equalizing gains prior to forming analog sums for trigger purposes. The gain of the VGA is variable over a 3:1 range using a 5 bits digital control, and the risetime is held to approximately 20 ns using switched compensation in the VGA. Details of the design and results from several prototype devices fabricated in 1.2 {micro}m Orbit CMOS are presented. A complete noise analysis of the integrating amplifier and the correlated sampling process is included as well as a comparison of calculated, simulated and measured results.
Date: November 1, 1997
Creator: Wintenberg, A.L.; Jones, J.P. Jr.; Young, G.R. & Moscone, C.G.
Partner: UNT Libraries Government Documents Department

Ring-imaging Cerenkov studies. Final performance report

Description: This project involved collaboration in the design, construction and testing of a prototype chamber capable of detecting Cerenkov rings. The chamber incorporated several novel techniques in that it used parallel-plate pad readout and a Cesium-iodide (CsI) solid photocathode. The pad system used gas multiplication where the gas was kept at low pressure to minimize photon losses due to absorption and back-scattering and to minimize ion collection times. Low pressure also lowers the chamber response to charged particles. The chamber gas was ethane at 20 torr and the chamber was operated at room temperature. The chamber was built at the University of Pennsylvania by a University of Puerto Rico graduate student, Jorge Millan. Initial tests at Pennsylvania using a hydrogen-discharge lamp indicated a quantum efficiency of 13% at 190 nm. The chamber was then tested in the M-Test beam line at Fermilab and behind the C3 beamline dump at Brookhaven Lab. Cerenkov rings were clearly observed with each photoelectron typically exciting one pad. On average each ring had five struck pads and only 10% of the events had hits in the center due to the charged particle. These results indicate that a RICH detector using a solid CsI photocathode coupled to a low-pressure, parallel-plate pad chamber is an excellent device for particle identification in high-rate environments when there is a need to cover large areas with minimum expense.
Date: March 13, 1997
Creator: Lopez, A. M.
Partner: UNT Libraries Government Documents Department

The atmospheric neutrino flavor ratio in Soudan 2

Description: The Soudan 2 collaboration has measured the atmospheric neutrino flavor ratio with 2.63 kiloton years of exposure. The measured flavor ratio is 0.67 {+-} 0.15(stat) + 0.04--0.06(syst). The neutrino induced horizontal muon flux has been measured to be {Phi}{sub {mu}} = (4.12 {+-} 1.1 {+-} 0.58) {times} 10{sup {minus}13} cm{sup {minus}2} sr{sup {minus}1} s{sup {minus}1}.
Date: October 1, 1997
Creator: Goodman, M. & Collaboration, Soudan 2
Partner: UNT Libraries Government Documents Department