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Systematics of mid-rapidity E{sub T} and multiplicity distributions in nucleus and nucleon collisions at AGS energies

Description: In the period 1986--1992, the E802 Collaboration at the BNL-AGS made systematic measurements of transverse energy (E{sub T}) emission in an electromagnetic calorimeter (PbGl) which covered the pseudorapidity interval 1.25 {le} {eta} {le} 2.50 and half the azimuth (where mid-rapidity for these energies is y{sub cm}{sup N N} {approx_equal} 1.6 - 1.7 depending the species). The other half of the azimuth was occupied by a 25 msr magnetic spectrometer with full particle identification. Runs were also taken with two different full-azimuth configurations of the PbGl, covering 1.25 {le} {eta} {le} 2.44, and also 1.3 {le} {eta} {le} 2.4. It was noticed that the shapes of the upper edges of the E{sub T} distributions, as represented for example by the p parameter in a gamma distribution fit, seemed to vary with the solid angle of the configuration. To systematically investigate this effect, the A-dependence and pseudorapidity-interval ({delta}{eta}) dependence of E{sub T} distributions in the half-azimuth electromagnetic calorimeter were measured for p+Be, p+Au, O+Cu, Si+Au and Au+Au collisions.
Date: December 31, 1998
Creator: Tannenbaum, M.J. & Collaboration, E802
Partner: UNT Libraries Government Documents Department

Proceedings of PIXEL98 -- International pixel detector workshop

Description: Experiments around the globe face new challenges of more precision in the face of higher interaction rates, greater track densities, and higher radiation doses, as they look for rarer and rarer processes, leading many to incorporate pixelated solid-state detectors into their plans. The highest-readout rate devices require new technologies for implementation. This workshop reviewed recent, significant progress in meeting these technical challenges. Participants presented many new results; many of them from the weeks--even days--just before the workshop. Brand new at this workshop were results on cryogenic operation of radiation-damaged silicon detectors (dubbed the Lazarus effect). Other new work included a diamond sensor with 280-micron collection distance; new results on breakdown in p-type silicon detectors; testing of the latest versions of read-out chip and interconnection designs; and the radiation hardness of deep-submicron processes.
Date: August 1, 1998
Creator: Anderson, D.F. & Kwan, S.
Partner: UNT Libraries Government Documents Department

Research in theoretical physics. Final report

Description: This report summarizes the research carried out under Grant DE-FG02-85ER40211. The main topics covered are: astroparticle physics at very high and ultrahigh energies; search for new physics by means of detectors of ultrahigh energy particles of extraterrestrial origin. Methods for searching in heavy quark decays for signatures of physics beyond the standard model are developed.
Date: June 1, 1998
Creator: Domokos, G. & Kovesi-Domokos, S.
Partner: UNT Libraries Government Documents Department

Final report of the High Energy Physics Group at the University of South Alabama, April 15, 1990--April 14, 1997

Description: The experimental high energy physics group at the University of South Alabama worked on three experiments conducted at the Fermi National Accelerator Laboratory. These experiments were E-705, E-771, and E-871. The group helped in taking data, analysis of data, and for one experiment in the construction of a new spectrometer. Experiment E-705 used 300 GeV/c p, {pi}{sup {minus}}, {anti p} and {pi}{sup +} on Li to study hadronic production of charmonium and direct photon production. The authors participated in the E-705 data analysis. They helped in the assembly of the E-771 spectrometer. E-771 used 800 GeV/c p-Si interactions to study hadronic beauty production and charmonium production. The groups task was to bring up the electromagnetic calorimeter and interface it into the data acquisition system. Off-line work done for the analysis of E-771 concentrated on the electromagnetic reconstruction package. Other work done in conjunction with E-771 included the development of a tracking program that used the Hough Transformation. In March of 1994, the group joined Experiment E-871. This experiment is a search for CP violation. The group took responsibility for the scintillation trigger hodoscopes to be used by the experiment.
Date: August 15, 1998
Creator: Jenkins, C.M. & Clark, R.K.
Partner: UNT Libraries Government Documents Department

MEGA -- A search for {mu} {r_arrow} e{gamma}

Description: The MEGA experiment is a search for the decay {mu} {r_arrow} e{gamma}. Even though there is no fundamental reason to expect lepton number to be a conserved quantity, processes such as {mu} {r_arrow} e{gamma} have not been observed. (The present upper limit for the branching ratio for {mu} {r_arrow} e{gamma} is 4.9 x 10{sup {minus}11}.) The minimal standard model of electroweak interactions, which is enormously successful, builds in lepton number conservation. However, the decay {mu} {r_arrow} e{gamma} is expected in many extensions to the standard model, in particular in supersymmetry models. The experimental signature for {mu} {r_arrow} e{gamma} from decays at rest is the observation of a positron and photon, each of 52.8 MeV , that are back-to-back, in time coincidence, and originate from a common spatial point. The MEGA detector consists of two spectrometers designed to measure the kinematic characteristics of positrons and photons to search for events with this signature. The primary difficulty in the analysis of these data has been the development of reconstruction algorithms that balance efficiency and resolution. Also, many calibrations and corrections are needed to get optimum resolutions. Most surviving candidate events are accidentals. Results of analysis are given.
Date: December 1, 1998
Creator: Mischke, R. E.
Partner: UNT Libraries Government Documents Department

Search for quark-lepton compositeness using the Drell-Yan process at D-Zero

Description: We present preliminary results on the search for quark-lepton compositeness using the Drell-Yan process in p{anti p} collisions at {radical}s = 1.8 TeV. If quarks and leptons were composite with common substructure, the dielectron mass spectrum would show an excess in the high mass region relative to the Standard model. We observe no such excess. We set a 95% confidence level lower limit on the compositness scale using a contact interaction model.
Date: September 1, 1998
Partner: UNT Libraries Government Documents Department

Particle physics with kaons, muons and neutrinos. Summary of JHF K-Arena working groups 1a/1b

Description: The areas of rare K and {mu} decays and of neutrino oscillations are very active at the present time, and there is little reason to doubt that this will continue to be the case in the JHF era. The session featured talks describing the present status and projected future activity in these areas.
Date: August 1, 1998
Creator: Kuno, Yoshitaka & Littenberg, L.
Partner: UNT Libraries Government Documents Department

Investigation of rare particle production in high energy nuclear collisions. Progress report, December 15, 1997--December 14, 1998

Description: The program is an investigation of the hadronization process through experimental measurement of rare particle production in high energy nuclear interactions. These interactions provide an environment similar in energy density to the conditions in the Big Bang. The authors are currently involved in two major experiments to study this environment, E896 at the AGS and STAR at RHIC. They have completed the first physics running of E896, a search for the H dibaryon and measurement of hyperon production in AuAu collisions, and are in the process of analyzing the data. They have prototyped the STAR trigger and are in the process of fabricating its components and installing them in the STAR detector.
Date: November 1, 1998
Creator: Crawford, H.J. & Engelage, J.
Partner: UNT Libraries Government Documents Department

The BRAHMS experiment at RHIC goals and status

Description: The BRAHMS experiment is designed to measure semi-inclusive spectra of charged hadron over a wide range of rapidity. It will yield information on particle production, both at central rapidity and in the baryon rich fragmentation region. Examples of measures for soft as well as for hard physics are presented. The present status of BRAHMS is discussed, as well as the plans for measurements in the first year of running at RHIC.
Date: December 1, 1998
Creator: Videbaek, F.
Partner: UNT Libraries Government Documents Department

Evidence of K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}: The BNL E787 1995 result (How did we get here)

Description: The kaon was studied very thoroughly since its discovery some 50 years ago. In the study of charged kaon branching ratios, it was noticed that K{sup +} {r_arrow} {pi}{sup 0}e{sup +}{nu}{sub e} is allowed while K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is not. The latter was then empirically classified as a forbidden decay, leading to the so called strangeness changing current rule. The decay K{sup +} {r_arrow} {pi}{sup 0}e{sup +}{nu}{sub e} is mediated by the strangeness changing charged current and its branching ratio is 4.8%. By contrast K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is a strangeness changing neutral current, which is forbidden. In 1970, the GIM model was introduced to explain this effect and in 1974, Gaillard and Lee calculated the K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} branching ratio to be on the order of 10{sup {minus}10}. In the current theory, the K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is mediated by a Flavor Changing Neutral Current (FCNC) in which the cancellation of the three quark generations should be complete down to second order except for the difference in the quark masses. The top quark is much heavier than the charm and up quarks, so that the cancellation is not complete. In other words, this decay is more dependent on the top sector. The measurement of K{sup +} {r_arrow}{pi}{sup +}{nu}{anti {nu}} branching ratio measures the modulus of the V{sub td} element of the CKM Matrix. The 1995 results of E787 were published in 1997. This report is focused on how the author achieved the goal of detecting events with such as small branching ratio.
Date: February 1, 1998
Creator: Chiang, I.H. & Collaboration, E787
Partner: UNT Libraries Government Documents Department

Studying the spin structure of the proton using the solenoidal tracker at RHIC

Description: The primary goal of RHIC is to produce nuclear matter under extremes of temperature and density sufficient to excite the QCD vacuum, resulting in the creation of a deconfined plasma of quarks and gluons. A second goal central to the RHIC scientific program is to advance the study of the spin structure of the proton significantly beyond what has been learned from deep inelastic scattering (DIS) measurements by studying spin asymmetries in strong processes involving the partonic constituents of polarized protons. After decades of being regarded as an inessential complication to the strong interaction at high energy, spin has again become a topic of considerable experimental and theoretical interest. This is largely due to the observation from DIS that the net contribution to the proton spin from the quark constituents ({approximately} 30%) is smaller than expected relative to the momentum carried in this sector. The RHIC accelerator will provide an unprecedented opportunity to fully explore the spin structure of the proton with high precision studies focused on measuring the spin-dependent parton distributions (valence quark, sea quark, gluon) of the proton. It is designed to operate both with high luminosity (10{sup 31}--10{sup 32} cm{sup {minus}2} sec{sup {minus}1}) and high polarization ({approximately} 70%). In addition, the energy range at RHIC ({radical}s = 200--500 GeV) is sufficiently high that spin effects in polarized proton interactions should be calculable once the spin structure of the proton is sufficiently understood. The experimental results will therefore provide a rigorous test of QCD. A further focus of the RHIC spin physics program will be to search for physics beyond the standard model. The increased sensitivity afforded by using polarized protons to study parity violation in inclusive jet production at high p{sub t} makes this exploration competitive with respect to ongoing searches using unpolarized beams.
Date: May 1, 1998
Creator: Hallman, T.J. & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

[Research in theoretical and experimental elementary particle physics. Final report]

Description: This report gives summaries of particle physics research conducted by different group members for Task A. A summary of work on the CLEO experiment and detector is included for Task B along with a list of CLEO publications. During the present grant period for Task C, the authors had responsibility for the design, assembly, and programming of the high-resolution spectrometer which looks for narrow peaks in the output of the cavity in the LLNL experiment. They successfully carried out this task. Velocity peaks are expected in the spectrum of dark matter axions on Earth. The computing proposal (Task S) is submitted in support of the High Energy Experiment (CLEO, Fermilab, CMS) and the Theory tasks.
Date: November 1, 1998
Partner: UNT Libraries Government Documents Department