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Search for lepton-family-number nonconservation

Description: A review of the status of lepton-family-number nonconservation is given. After a brief historical and theoretical discussion, a description of how experimental searches for lepton-family-number nonconservation are performed is presented. Finally, a summary of the results from past experiments and prospects for future experiments is given.
Date: January 1, 1986
Creator: Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Monochromatic neutral kaon beam

Description: A design for a monochromatic, neutral kaon (K/sup 0/) beam, which could be constructed at a Kaon Factory, is described. Possible uses of such a beam are discussed.
Date: July 1, 1980
Creator: Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Note on the decays. pi. /sup 0/. -->. nu nu. '

Description: Phenomenological aspects of ..pi../sup 0/ ..-->.. ..nu nu..' are considered. From the existing experimental information, an upper limit GAMMA(..pi../sup 0/ ..-->.. ..nu nu..')/GAMMA(..pi../sup 0/ ..-->.. all) < 2.4 x 10/sup -5/ (90% C.L.) is deduced. Possible mechanisms which can give rise to this process are discussed. Branching ratios of the order of 10/sup -7/ for decays into the known neutrinos (..nu../sub e/,..nu../sub ..mu../) are found possible. Rates comparable to the experimental limit for decays into final states involving additional neutrinos (massive or massless) cannot be ruled out.)
Date: January 1, 1980
Creator: Herczeg, P. & Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Summary: Neutrinos and nonaccelerator physics

Description: This paper contains brief synopsis of the following major topics discussed in the neutrino and nonaccelerator parallel sessions: dark matter; neutrino oscillations at accelerators and reactors; gamma-ray astronomy; double beta decay; solar neutrinos; and the possible existence of a 17-KeV neutrino. (LSP)
Date: January 1, 1991
Creator: Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Determination and study of the cosmic-ray composition above 100 TeV

Description: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project was to develop a new technique using ground-based measurements to determine the cosmic-ray composition at energies around 10{sup 15} eV (the knee in the cosmic-ray spectrum). Cosmic rays are high-energy nuclei that continuously bombard the earth. Though cosmic rays were first detected in the 1870s it wasn`t until 1915 that their cosmic origin was established. At present, the authors still do not know the source of cosmic rays. At energies above 50 TeV (1 TeV = 1 trillion electron-volts) they do not know the composition of the cosmic rays. At about 5 PeV (1PeV = 10{sup 15} eV) the cosmic ray spectrum steepens. Knowledge of the composition above and below this point can help determine the origin of cosmic rays.
Date: November 1, 1998
Creator: Sinnis, G.; Haines, T.J. & Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Study of rare muon decay modes with the crystal box

Description: We report on a search for the lepton family-number-nonconserving decays ..mu../sup +/..-->..e/sup +/e/sup -/e/sup +/, ..mu../sup +/..-->..e/sup +/..gamma.., and ..mu../sup +/..-->..e/sup +/..gamma gamma.., using the Crystal Box detector at LAMPF. The experiment was run in the stopped muon channel at LAMPF during the winter and summer of 1984. Muons were stopped in the middle of a detector system consisting of a cylindrical drift chamber, a plastic scintillator hodoscope, and a segmented array of sodium iodide crystals. The sodium iodide surrounded the hodoscope and drift chamber. Events consistent with any of the above decays were recorded. The off-line data analysis imposed requirements on the timing, vertex location, and energy and momentum conservation for each event. Radioactive sources, conventional muon decay spectra, and photons from the process ..pi../sup -/p..-->..n..gamma.. and ..pi../sup -/p..-->..n..pi../sup 0/ were used to provide energy calibration and resolution estimates. The inner bremsstrahlung processes ..mu../sup +/..-->.. e/sup +/..gamma nu..anti..nu.. and ..mu../sup +/..-->..e/sup +/e/sup -/e/sup +/..nu..anti..nu.. were observed at the expected rates. Details of the detector, the data analysis, and our latest bounds for the branching ratios will be presented. 33 figs.
Date: January 1, 1985
Creator: Sandberg, V.; Bolton, R.D.; Bowman, J.D.; Carlini, R.D.; Copper, M.D.; Doung-Van, M. et al.
Partner: UNT Libraries Government Documents Department

Progress report on recent rare muon decay experiments at the Los Alamos Meson Physics Facility

Description: A search has been performed for the decays ..mu.. ..-->.. eee, ..mu.. ..-->.. e..gamma.., and ..mu.. ..-->.. e..gamma gamma.. with a sensitivity in the branching ratios at the level of 10/sup -10/. The experiment used a separated, 26 MeV/c ..mu../sup +/ beam with an average intensity of 300kHz. A total of 2.2 x 10/sup 11/ muon decays were examined for the present result. The detector for the experiment is the Crystal Box, which consists of a cylindrical drift chamber surrounded by 396 NaI(T1) crystals. A layer of scintillation counters in front of the crystals provided timing for electrons and veto for photons. The energy resolution for electrons and photons is approx. 6% (FWHM). The position resolution of the drift chamber is 350 ..mu..m leading to a vertex cut with a rejection of 10/sup 3/ for ..mu.. ..-->.. eee. The timing resolution is approx. 300 ps the scintillators and approx. 1 ns from the crystals. No candidate for ..mu.. ..-->.. eee has been found, yielding an upper limit for the branching ratio of B/sub ..mu..3e/ < 1.3 x 10/sup -10/ (90% C.L.). 21 references.
Date: January 1, 1984
Creator: Hogan, G.E.; Bolton, R.D.; Bowman, J.D.; Carlini, R.; Cooper, M.D.; Duong-van, M. et al.
Partner: UNT Libraries Government Documents Department

Milagro Contributions to XXVI International Cosmic Ray Conference

Description: Milagrito, a prototype for the Milagro detector, operated for 15 months in 1997--8 and collected 8.9 x 10{sup 9} events. It was the first extensive air shower (EAS) array sensitive to showers initiated by primaries with energy below 1 TeV. The shadows of the sun and moon observed with cosmic rays can be used to study systematic pointing shifts and measure the angular resolution of EAS arrays. Below a few TeV, the paths of cosmic rays coming toward the earth are bent by the helio- and geo-magnetic fields. This is expected to distort and displace the shadows of the sun and the moon. The moon shadow, offset from the nominal (unreflected) position, has been observed with high statistical significance in Milagrito. This can be used to establish energy calibrations, as well as to search for the anti-matter content of the VHE cosmic ray flux. The shadow of the sun has also been observed with high significance.
Date: August 1, 1999
Creator: Hoffman, C.M.; Haines, T.J.; Sinnis, G.; Miller, R.S. & Thompson, N.T.
Partner: UNT Libraries Government Documents Department

Search for the muon-number violating decay. mu. -->. e/sup +/e/sup +/e/sup -/

Description: A search has been performed for the muon-number-violating decay ..mu.. ..-->.. e/sup +/e/sup +/e/sup -/. No candidate event has been found, yielding an upper limit for the branching ratio of B/sub ..mu..3e/ < 1.3 x 10/sup -10/ (90% C.L.). From part of the data taken with a trigger that enhanced ..mu../sup +/ ..-->.. e/sup +/e/sup +/e/sup -/ anti nu/sub ..mu../nu/sub e/ events, 11 such events were observed. They agree in number and spectra with expectations based on standard electroweak theory. 9 references.
Date: January 1, 1984
Creator: Bolton, R.D.; Bowman, J.D.; Carlini, R.; Cooper, M.D.; Duong-van, M.; Frank, J.S. et al.
Partner: UNT Libraries Government Documents Department

Current Experiments in Particle Physics (September 1996)

Description: This report contains summaries of current and recent experiments in Particle Physics. Included are experiments at BEPC (Beijing), BNL, CEBAF, CERN, CESR, DESY, FNAL, Frascati, ITEP (Moscow), JINR (Dubna), KEK, LAMPF, Novosibirsk, PNPI (St. Petersburg), PSI, Saclay, Serpukhov, SLAC, and TRIUMF, and also several proton decay and solar neutrino experiments. Excluded are experiments that finished taking data before 1991. Instructions are given for the World Wide Web (WWW) searching of the computer database (maintained under the SLAC-SPIRES system) that contains the summaries. This report contains full summaries of 180 approved current and recent experiments in elementary particle physics. The focus of the report is on selected experiments which directly contribute to our better understanding of elementary particles and their properties such as masses, widths or lifetimes, and branching fractions.
Date: September 1, 1996
Creator: Galic, H.; Lehar, F.; Klyukhin, V.I.; Ryabov, Yu.G.; Bilak, S.V.; Illarionova, N.S. et al.
Partner: UNT Libraries Government Documents Department

Search for rare muon and pion decay modes with the crystal box detector

Description: New experiental upper limits for the branching ratios of the lepton-family-number nonconserving decays ..mu../sup +/ ..-->.. e/sup +/..gamma.. and ..mu../sup +/ ..-->.. e/sup +/..gamma gamma.. are presented. A new determination of ..gamma.., the ratio of pion axial vector to vector form factors, from radiative pion decay is also reported. These results are from data taken with the Crystal Box detector at LAMPF. 11 refs., 7 figs.
Date: January 1, 1986
Creator: Piilonen, L.E.; Bolton, R.D.; Bowman, J.D.; Cooper, M.D; Frank, J.S.; Hallin, A.L. et al.
Partner: UNT Libraries Government Documents Department

Search for the decay. mu. /sup +/. -->. e/sup +/. gamma

Description: This Letter reports a new experimental search for the family-number-nonconserving decay ..mu../sup +/ ..-->.. e/sup +/..gamma... There is no evidence for the presence of this decay mode. The upper limit for the branching ratio is GAMMA(..mu.. ..-->.. e..gamma..)/GAMMA(..mu.. ..-->.. enu anti nu) < 4.9 x 10/sup -11/ (90% C.L.). 13 refs., 3 figs.
Date: January 1, 1986
Creator: Hoffman, C.M.; Bolton, R.D.; Bowman, J.D.; Cooper, M.D.; Frank, J.S.; Heusi, P.A. et al.
Partner: UNT Libraries Government Documents Department

New results for rare muon decays

Description: Branching-ratio limits obtained with the Crystal Box detector are presented for the rare muon decays ..mu.. ..-->.. eee, ..mu.. ..-->.. e..gamma.., and ..mu.. ..-->.. e..gamma gamma... These decays, which violate the conservation of separate lepton-family numbers, are expected to occur in many extensions to the standard model. We found no candidates for the decay ..mu.. ..-->.. eee, yielding an upper limit for the branching ratio of B/sub ..mu..3e/ < 3.1 x 10/sup -11/ (90% C.L.). A maximum-likelihood analysis of the ..mu.. ..-->.. e..gamma.. candidates yields an upper limit of B/sub ..mu..e..gamma../ < 4.9 x 10/sup -11/ and an analogous analysis of ..mu.. ..-->.. e..gamma gamma.. candidates gives an upper limit of B/sub ..mu..e..gamma gamma../ < 7.2 x 10/sup -11/. These results strengthen the constraints on models that allow transitions between lepton families.
Date: January 1, 1986
Creator: Mischke, R.E.; Bolton, R.D.; Bowman, J.D.; Cooper, M.D.; Frank, J.S.; Hallin, A.L. et al.
Partner: UNT Libraries Government Documents Department

Discovery of TeV Gamma-Ray Emission from the Cygnus Region

Description: The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at {approx}12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or other sources of TeV gamma rays in the region.
Date: November 28, 2006
Creator: Abdo, A.A.; Allen, B.; Berley, D.; Blaufuss, E.; Casanova, S.; Chen, C. et al.
Partner: UNT Libraries Government Documents Department

A Measurement of the Spatial Distribution of Diffuse TeV Gamma Ray Emission from the Galactic Plane with Milagro

Description: Diffuse {gamma}-ray emission produced by the interaction of cosmic-ray particles with matter and radiation in the Galaxy can be used to probe the distribution of cosmic rays and their sources in different regions of the Galaxy. With its large field of view and long observation time, the Milagro Gamma Ray Observatory is an ideal instrument for surveying large regions of the Northern Hemisphere sky and for detecting diffuse {gamma}-ray emission at very high energies. Here, the spatial distribution and the flux of the diffuse {gamma}-ray emission in the TeV energy range with a median energy of 15 TeV for Galactic longitudes between 30{sup o} and 110{sup o} and between 136{sup o} and 216{sup o} and for Galactic latitudes between -10{sup o} and 10{sup o} are determined. The measured fluxes are consistent with predictions of the GALPROP model everywhere except for the Cygnus region (l {element_of} [65{sup o}, 85{sup o}]). For the Cygnus region, the flux is twice the predicted value. This excess can be explained by the presence of active cosmic ray sources accelerating hadrons which interact with the local dense interstellar medium and produce gamma rays through pion decay.
Date: May 14, 2008
Creator: Abdo, A.A.; Allen, B.; Aune, T.; Berley, D.; Blaufuss, E.; Casanova, S. et al.
Partner: UNT Libraries Government Documents Department

The status of CYGNUS experiment: Past, present, and future

Description: The CYGNUS experiment, located in Los Alamos, NM, has been continuously operating since April 2, 1986. The experiment consists of an air shower array and an associated 44 m/sup 2/ muon detector; its large size, good angular resolution, muon detection, and low energy threshold make it a unique experiment among those currently operating. The experiment has undergone continuous expansion in several stages since it began operation. The experiment, its expansion, and further plans for the further will be described. 6 refs., 9 figs.
Date: January 1, 1989
Creator: Haines, T.J.; Berley, D.; Chang, C.Y.; Dingus, B.L.; Goodman, J.A.; Stark, M. et al.
Partner: UNT Libraries Government Documents Department

Measurement of proton induced radiation damage to CMOS transistors and pin diodes

Description: As part of our program to develop a silicon tracking device for the SSC we have exposed radiation-hard CMOS transistors and PIN diodes to the 800 MeV LAMPF proton beam. The fluences accumulated in a week corresponded to the expected radiation levels of about 10 SSC years. We determine the leakage current constants for PIN diodes and threshold voltage shifts for CMOS transistors under different biasing conditions. One of the main requirements for detectors and front-end electronics at the SSC is to be radiation-resistant. The SSC Workshop on Radiation Levels in the SSC found that, for example, a silicon tracking device at a radius of 10 cm has to survive a yearly dose of about 0.3 MRad due to charged particles and a yearly neutron fluence of a few times 10{sup 12} neutrons/cm{sup 2} at the design luminosity of 10{sup 33} cm{sup -2}sec{sup -1}. 13 refs., 3 figs., 1 tab.
Date: January 1, 1990
Creator: Ziock, H.J.; Hoffman, C.M.; Holtkamp, D.; Kinnison, W.W.; Milner, E.C.; Sommer, W.F. (Los Alamos National Lab., NM (USA)) et al.
Partner: UNT Libraries Government Documents Department

A low threshold EAS (extensive-air-shower) array for gamma-ray astronomy at Los Alamos

Description: A new type of extensive-air-shower (EAS) array is described that achieves a low energy threshold, large area, high duty factor and large muon coverage. By placing a regularly-spaced grid of phototubes just below the surface of a shallow pond, the Cherenkov light of particles in an air shower striking the water can be detected, resulting in a primary energy threshold of less than 1 TeV. This highly sensitive array can thus be used to span the gap of information between the existing air Cherenkov techniques at 1 TeV and the existing EAS arrays at 100 TeV. 5 refs., 3 figs.
Date: January 1, 1990
Creator: Burman, R.L.; Hoffman, C.M.; Nagle, D.E.; Potter, M.E.; Sandberg, V.; Berley, D. et al.
Partner: UNT Libraries Government Documents Department

CYGNUS Collaboration contributions to the twenty-second ICRC

Description: This report contains short papers on the cygnus experiments on the detection of cosmic air showers from distant sources such as nebulae, galaxies, x-ray sources, etc. (LSP).
Date: August 1, 1991
Creator: Alexandreas, D.E.; Biller, S.; Dion, G.M.; Lu, X.Q.; Yodh, G.B. (California Univ., Irvine, CA (USA)); Berley, D. et al.
Partner: UNT Libraries Government Documents Department

Search for UHE emission from 4U0115+63

Description: We report here the preliminary results of our observations of the sporadic x-ray binary system 4U0115 + 63. The CYGNUS air shower array has been collecting data since April 1986. No significant excess is seen from the direction of this source, nor any correlation with its 24-day orbital period. A 90% confidence-level upper limit on the flux from 4U0115 + 63 is 2.8 {times} 10{sup {minus}13} cm{sup {minus}2} s{sup {minus}1} above 50 TeV. This flux limit is considerably lower than those reported by other UHE experiments. Search for periodicity at the neutron star frequency is in progress. 12 refs., 3 figs., 1 tab.
Date: January 1, 1990
Creator: Alexandreas, D.E.; Allen, R.C.; Biller, S.D.; Dion, G.M.; Lu, X-Q.; Vishwanath, P.R. et al.
Partner: UNT Libraries Government Documents Department

Relative muon content of UHE showers associated with Hercules X-1

Description: A further analysis is presented of the muon content associated with the July, 1986 UHE observation of the Hercules X-1 system, previously reported by the CYGNUS collaboration. The probability for observing comparable muon content in a set of background'' showers similar to those of the Hercules burst is given. 3 refs., 2 tabs.
Date: January 1, 1989
Creator: Alexandreas, D.E.; Allen, R.C.; Biller, S.; Dion, G.; Lu, X-Q; Vishwanath, P.R. et al.
Partner: UNT Libraries Government Documents Department

Status of the expansion of the CYGNUS array at Los Alamos

Description: The CYGNUS air shower array, located in Los Alamos, New Mexico, has been operating since April, 1986. The expansion of the array from 108 to 200 counters is described along with the increase in muon detection area. The new array, to be fully operational by the end of 1989, will have three times the sensitivity to UHE sources. 5 refs., 2 figs.
Date: January 1, 1989
Creator: Berley, D.; Chang, C.Y.; Dingus, B.L.; Goodman, J.A.; Haines, T.J.; Stark, M. et al.
Partner: UNT Libraries Government Documents Department