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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

Possibility of studying. nu. /sub e/ and anti. nu. /sub e/ interactions at a Kaon Factory

Description: The possibility of observing ..nu../sub e/- and anti ..nu../sub e/-induced reactions at a high-flux Kaon Factory is discussed. A recently suggested neutrino beam derived from K/sub L//sup 0/ decays is the enriched source of ..nu../sub e/ and anti ..nu../sub e/. Some specific measurements which are feasible are described.
Date: March 1, 1981
Creator: Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Prospects in lepton-flavor violation

Description: The theoretical and experimental situation regarding lepton-flavor conservation is reviewed and upcoming experiments are described. It is concluded that future improvements in experimental sensitivities will require higher flux, higher quality muon and kaon beams.
Date: January 1, 1982
Creator: Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Using K/sup +/ decays as a source of tagged. pi. /sup 0/'s

Description: It appears that using K/sup + -/ ..-->.. ..pi../sup +/..pi../sup 0/ is a useful source of tagged ..pi../sup 0/'s to investigate the rare decays ..pi../sup 0/ ..-->.. e/sup +/e/sup -/, ..pi../sup 0/ ..-->.. ..gamma gamma..approx., and ..pi../sup 0/ ..-->.. ..nu.. anti ..nu... Present accelerator intensities may be sufficient to study the first process, although a detailed experimental design may show that higher intensities are needed. Higher flux beams clearly are needed to achieve the best sensitivity to ..pi../sup 0/ ..-->.. ..nu.. anti ..nu.. and ..pi../sup 0/ ..-->.. ..gamma gamma..approx..
Date: January 1, 1982
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

Are there really any experimental limits on a light Higgs boson

Description: The experimental evidence regarding a light Higgs boson is reviewed. It is shown that a light Higgs boson with almost any mass between 14 MeV/c/sup 2/ and 1 GeV/c/sup 2/ is still allowed by existing data. The only limit in this range comes from B decay data which, for sufficiently large values of the top quark mass, excludes a Higgs boson with a mass between 2m/sub ..mu../ and /approximately/700 MeV/c/sup 2/. Discussions of light Higgs boson emission in the decays of K, ..pi.., ..mu.., /tau/, /eta/', and GAMMA are also given. 29 refs., 2 figs.
Date: January 1, 1988
Creator: Raby, S.; West, G.B. & Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Search for parity violation in polarized proton scattering at 6 GeV/c. [A symmetry, preliminary results]

Description: A small deviation is sought from the parity symmetry in proton--nucleon scattering. For 6 GeV polarized protons on H/sub 2/O a preliminary value of Ay = ..delta..sigma/P2sigma is found for the longitudinal asymmetry (include systematic errors) using ion chamber detectors, and Ay = (include systematic errors) using scintillator detectors. 4 references
Date: January 1, 1978
Creator: Nagle, D.E.; Bowman, J.D. & Hoffman, C.M.
Partner: UNT Libraries Government Documents Department

Measuring pion beta decay with high-energy pion beams

Description: Improved measurements of the pion beta decay rate are possible with an intense high-energy pion beam. The rate for the decay {pi}{sup +} {yields} {pi}{sup 0}e{sup +}v{epsilon} is predicted by the Standard Model (SM) to be R({pi}{sup +} {yields} {pi}{sup 0}e{sup +}v{epsilon}) = 0.3999{plus_minus}0.0005 s{sup {minus}1}. The best experimental number, obtained using in-flight decays, is R({pi}{sup +} {yields} {pi}{sup 0}e{sup +}v{epsilon}) = 0.394 {plus_minus} 0.015 s{sup {minus}1}. A precise measurement would test the SM by testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix for which one analysis of the nuclear beta decay data has shown a 0.4% discrepancy. Several nuclear correction factors, needed for nuclear decay, are not present for pion beta decay, so that an experiment at the 0.2% level would be a significant one. Detailed study of possible designs will be needed, as well as extensive testing of components. The reduction of systematic errors to the 0.1% level can only be done over a period of years with a highly stable apparatus and beam. At a minimum, three years of occupancy of a beam line, with 800 hours per year, would be required.
Date: February 1, 1993
Creator: McFarlane, W. K. & 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

Los Alamos Crystal Box experiment: a search for. mu. -->. e. gamma. ,. mu. -->. e. gamma gamma. , and. mu. -->. eee

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 surface muon beam at LAMPF with an average intensity of 300 kHz. A total of > 10/sup 11/ muon decays was 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(Tl) crystals. A layer of scintillation counters in front of the crystals provided timing for electrons and a 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. 400 ps from the scintillators and approx. 1 ns from the crystals. From these values, the eee and e..gamma gamma.. limits are expected to be background free.
Date: January 1, 1984
Creator: Hallin, A.L.; Bolton, R.D.; Bowman, J.D.; Duong-van, M.; Frank, J.S.; Heusi, P.A. et al.
Partner: UNT Libraries Government Documents Department

Test of radiation hardness of CMOS transistors under neutron irradiation

Description: We have tested 2 micron CMOS test structures from various foundries in the LAMPF Beam stop for radiation damage under prolongued neutron irradiation. The fluxes employed covered the region expected to be encountered at the SSC and led to fluences of up to 10/sup 14/ neutrons/cm/sup 2/ in about 500 hrs of running. We show that test structures which have been measured to survive ionizing radiation of the order MRad also survive these high neutron fluences. 5 refs., 4 figs.
Date: January 1, 1989
Creator: Sadrozinski, H.F.W.; Rowe, W.A.; Seiden, A.; Spencer, E.; Hoffman, C.M.; Holtkamp, D. 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

Measuring pion beta decay with high-energy pion beams

Description: Improved measurements of the pion beta decay rate are possible with an intense high-energy pion beam. The rate for the decay [pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon] is predicted by the Standard Model (SM) to be R([pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon]) = 0.3999[plus minus]0.0005 s[sup [minus]1]. The best experimental number, obtained using in-flight decays, is R([pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon]) = 0.394 [plus minus] 0.015 s[sup [minus]1]. A precise measurement would test the SM by testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix for which one analysis of the nuclear beta decay data has shown a 0.4% discrepancy. Several nuclear correction factors, needed for nuclear decay, are not present for pion beta decay, so that an experiment at the 0.2% level would be a significant one. Detailed study of possible designs will be needed, as well as extensive testing of components. The reduction of systematic errors to the 0.1% level can only be done over a period of years with a highly stable apparatus and beam. At a minimum, three years of occupancy of a beam line, with 800 hours per year, would be required.
Date: January 1, 1993
Creator: McFarlane, W.K. (Superconducting Super Collider Lab., Dallas, TX (United States) Temple Univ., Philadelphia, PA (United States)) & Hoffman, C.M. (Los Alamos National Lab., NM (United States))
Partner: UNT Libraries Government Documents Department