124136703
Improved Constraints on the Neutralino Cold Dark Matter Candidate from the Search for Chargino and Neutralino Production Using the OPAL Detector at 170 ÷ 172 Gev at LEP
New limits on the cold dark matter candidate, the lightest neutralino \(\left( {\tilde x_1^0} \right)\), are obtained from a search for charginos and neutralinos using a data sample of 10.3 pb−1 at the center-of-mass energies of √s =170 and 172 GeV with the OPAL detector at LEP.
120215204
Monolithic CMOS pixel detector for international linear collider vertex detection
A monolithic CMS pixel detector is under development for an ILC experiment. This chronopixel array provides a time stamp resolution of one bunch crossing, a critical feature for background suppression. The status of this effort is summarized.
111420431
Ideas on DC-DC Converters for Delivery of Low Voltage and High Currents for the SLHC / ILC Detector Electronics in Magnetic field and Radiation environments
For more efficient power transport to the electronics embedded inside large colliding beam detectors, we explore the feasibility of supplying 48 Volts DC and using local DCDC conversion to 2 V (or lower, depending upon on the lithography of the embedded electronics) using switch mode regulators located very close to the front end electronics. These devices will be exposed to high radiation and high magnetic fields, 10 – 100 Mrads and 2 4 Tesla at the SLHC, and 20 Krads and 6 Tesla at the ILC.
2708913
Monolithic CMOS Pixel Detectors for ILC Vertex Detection
A CMOS pixel vertex detector suited for use at the International Linear Collider (ILC) is proposed. The proposed detector consists of 50µm ◊ 50µm macropixels, each with integrated bunch clock memory, on top of 5µm ◊ 5µm micropixels that record amplitude information. The micropixels integrate over all bunch crossing in a train. Using the time recorded by the macropixels, the fine position measurements made in the micropixels can be associated to only a few of the 3000 bunch crossings in a bunch train.
16601897
Mechanisms affecting performance of the BaBar resistive plate chambers and searches for remediation
The BaBar experiment at PEPII relies on the instrumentation of the flux return (IFR) for both muon identification and KL detection. The active detector is composed of resistive plate chambers (RPCs) operated in streamer mode. Since the start of operation the RPCs have suffered persistent efficiency deterioration and dark current increase problems. The ‘‘autopsy’’ of bad BaBar RPCs revealed that in many cases uncured linseed oil droplets had formed on the inner surface of the Bakelite plates, leading to current paths from oil ‘‘stalagmites’’ bridging the 2mm gap. In this paper, a possible model of this ‘‘stalagmite’’ formation and its effect on the dark current and efficiency of RPC chambers is presented. Laboratory test results strongly support this model. ARTICLE IN PRESS *Corresponding author. Tel.: +1-609-258-4391; fax: +1-609-258-6360. E-mail address: changguo@princeton.edu (C. Lu). 0168-9002/03/$ see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-9002(03)01292-0 Based upon this model we are searching for solutions to eliminate the unfavorable effect of the oil stalagmites. The lab tests show that the stalagmite resistivity increases dramatically if exposed to the air, an observation that points to a possible way to remedy the damage and increase the efficiency. We have seen that flowing an oxygen gas mixture into the chamber helps to polymerize the uncured linseed oil. Consequently, the resistivity of the bridged oil stalagmites increases, as does that of the oil coating on the frame edges and spacers, significantly reducing the RPC dark currents and low-efficiency regions. We have tested this idea on two chambers removed from BaBar because of their low efficiency and high dark current. These test results are reported in the paper, and two other remediation methods also mentioned. We continue to study this problem, and try to find new treatments with permanent improvement. r 2003 Elsevier Science B.V. All rights reserved.
116064451
Chargino and Neutralino Mass Reconstruction for Small Mass Difference Non-Universal Sugra Points
A collapsible, movable apparatus, for containing health-sports devices and equipment, which includes a telescoping post support having at least two telescoping segments and a ratchet device for moving each of the adjacent telescoping segments in relation to each other. There is a support adopted to fit slideably on the top telescoping segment without overlapping onto the next telescoping segment. A large horizontally-positioned ring is mounted on the support. A platform is pivotally mounted under the ring so as to be able to swing downwardly when unconnected from the ring. Also, a basketball backboard is vertically mounted to the top portion of the top telescoping segment. The bottom end of the telescoping post is adapted to fit into a tube positioned in the ground or other horizontal surface.
121386932
Polarization in p-p elastic scattering at large four-momentum transfers
New results are presented from the continuation of an experiment designed to study the polarization in elastic p-p scattering at large four- momentum transfers. A high intensity unpolarized proton beam of momentum 12.3 GeV/c was incident on a propanediol polarized porton target and both final-state protons were detected and momentum analyzed in multiwire proportional chamber spectrometers. The measurements spanned the t range 1.5 < absolute t < 6.2 (GeV/ c)$sup 2$. The results are discussed in the framework of optical, exchange, and parton models. (AIP)
117954951
Planned Spin Studies at the Large Hadron Collider
This note summarizes how quantum spin can elucidate the physics of new energy regimes and presents a selection of planned studies at the LHC in which spin is expected to have special relevance.
115209317
Advances in the Study of Spin Effects in Nucleon-Nucleon Scattering at Small and Intermediate Momentum Transfers
There has been remarkable progress made in the field of high energy physics in the past five years. We have recently witnessed the discovery of new quantum numbers, the spectra of particles associated with these quantum numbers, and a much improved understanding of the role that all quantum numbers play in high energy interactions. With the wide assortment of experiments and studies being conducted in high energy physics at any one time, it is very easy for one to get the impression that, the activity in the field is highly unfocused. On the one hand, it is precisely this apparent unfocused nature that has given rise to much of the excitement and richness of the field. On the other hand, as one examines the situation more closely, one finds that much of the effort in the field is indeed directed toward the solution of a few central problems. One of these problems which I will continually refer to today is that of understanding the details of the structure of the elementary particles. This problem—one of the most fascinating and most difficult problems ever tackled by man-can be approached from several different angles.
117806093
Preliminary Polarization Results at Fermilab Energies
This paper describes the jet target, the superconducting spectrometer and the polarimeter used to measure the recoil proton polarization in an Indiana University experiment at the Fermi National Accelerator Laboratory. Analysis procedures and data checks are explained and preliminary results are presented and compared with model predictions. The future plans of the experiment are also discussed.
117801509
Lambda/b polarization study in the ATLAS experiment.
From preliminary studies it has been estimated that approximately 75000Λb will be available in the first years of the ATLAS running with integrated luminosity of 30fb−1, and we will be able to measure the polarization with accuracy of about 2%. In this paper we present the technical feasibility of measuring the polarization of Λb hyperons in ATLAS experiment.