R. Carlini

Limits on the neutrino magnetic moment from a measurement of neutrino-electron elastic scattering☆

Abstract Upper bounds on the magnetic moments of muon neutrinos and electron neutrinos are inferred from a measurement of neutrino-electron elastic scattering. The limits obained are: μ ν e −10 μ Bohr (90%CL) and μ ν ¬ −10 μ Bohr (90% CL).

RF Cavities with Transversely Biased Ferrite Tuning

Earley et al.1 suggested that ferrite tuned rf cavities have lower ferrite power dissipation if the ferrite bias field is perpendicular rather than parallel to the rf magnetic field. A 50-84 MHz cavity has been constructed in which ferrite can be biased either way. Low power measurements of six microwave ferrites show that the magnetic Qs of these ferrites under perpendicular bias are much higher than under parallel bias, and that the high Q region extends over a much wider range of rf permeability. TDK Y-5 ferrite was found to have a magnetic Q of 10,800, 4,800, 1,200 and 129 at rf permeabilities of 1.2, 2.4, 3.7 and 4.5, respectively. Measurements of perpendicularly biased ferrite at various power levels were made in a coaxial line cavity. The Q of Y-5 ferrite was found to decrease by less than a factor of 2 as the power density in the ferrite was increased to 1.3 W/cm3 . A cavity design for a 6 GeV, high current, rapid cycling synchrotron using transversely biased ferrite tuning is described.

A High-Q Ferrite-Tuned Cavity

Rapid cycling proton synchrotrons, such as the proposed LAMPF II accelerator, require approximately 10 MV per turn rf with 17% tuning range near 50 MHz. The traditional approach to ferrite-tuned cavities uses a ferrite which is longitudinally biased (rf magnetic field parallel to bias field). This method leads to unacceptably high losses in the ferrite. At Los Alamos, we are developing a cavity with transverse bias to the bias field) making use of the tensor permeability of the ferrite. Initial tests of a small (10-cm-diam) quarter-wave singly re-entrant cavity tuned by several different ferrites indicate that the losses in the ferrite can be made negligible compared with the losses due to the surface resistivity of the copper cavity. Details of the test results will be presented.

A detector system for the study of intermediate energy neutrino interactions

Abstract A 15 t fine-grained neutrino detector and high efficiency anticoincidence system are in operation at the LAMPF beam stop, an intense source of neutrinos with a maximum energy of 53 MeV. The primary use of this equipment is in an experiment which is directed towards the observation and cross section measurement of the ν e e − elastic scattering reaction. The design, operation, and performance of the apparatus is reported.

Search for the exotic decay μ+→e+ν̄eνμ

Abstract We search for the exotic decay μ+→e+ ν eνμ as a test of lepton number conversation. An exposure of ≈1020 μ+ -decay neutrinos to a 15 ton detector leads to a new upper bound for the branching ratio, RϵΓ(μ + →e + ν e ν μ /Γ(μ + →all), R .

Cygnus experiment at Los Alamos

The Cygnus experiment at Los Alamos National Laboratory has been designed to study, with high angular accuracy, point sources of gamma rays above 1014 eV. The experimental detector consists of an air shower array to observe gamma ray showers and a shielded, large area track detector to study the muon content of the showers. In this paper we present preliminary data from the array and describe its performance.

Low noise ionization chambers for use in transmission measurements with medium and high energy beams

Abstract We have investigated requirements for an integrating-type ion chamber that performs with signal fluctuations (noise) near the 1/√N counting statistics level. A large noise contribution occurs when the chamber collection foils intercept a beam of particles whose energy exceeds spallation production threshold. Experimental results demonstrate the source of this noise to be the production of low-energy spallation products in the plates and gas of the chamber. Delta rays also contribute to the noise, but not as severely. We have developed hydrogen-filled ion chambers with longitudinal collection plates that successfully eliminate the spallation contribution. With such chambers, noise improvement is typically a factor of 15 over chambers of conventional design.

A stereo, cylindrical drift chamber for muon decay experiments at LAMPF

Abstract A stereo, cylindrical drift chamber has been built for use in a search for rare decay modes of the muon at LAMPF. This chamber (part of the Crystal Box detector) has 728 cells on eight concentric annuli at alternating angles of 10° from the chamber axis and with radii from 105 to 220 mm. The basic cell cross section is (9 × 10) mm 2 and the inter-layer spacing is 4.7 mm. Preliminary results show the single wire efficiencies to be greater than 99%. Based on results obtained from prototype chambers, we hope to achieve 170 ≃m resolution (including multiple scattering) when TDC offsets and sense wire locations found in a careful inspection of the endplates are added to the track finding algorithm.

A progress report on recent rare muon decay experiments at the los alamos meson physics facility

Abstract A search has been performed for the decays μ → eee, μ → e γ , and μ → eγγ with a sensitivity in the branching ratios at the level of 10 −10 . The experiment used a separated, 26 MeV/c μ + beam with an average intensity of 300kHz. A total of 2.2 × 10 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 a veto for photons. The energy resolution for electrons and photons is ≈6% (FWHM). The position resolution of the drift chamber is 350 μm leading to a vertex cut with a rejection of 10 3 for μ → eee. The timing resolution is ≈300 ps from the scintillators and ~1 ns from the crystals. No candidate for μ → eee has been found, yielding an upper limit for the branching ratio of B μ 3e −10 (90% C.L.).

The Crystal Box: Rare decays of the muon

Development of the Crystal Box Spectrometer at the Clinton P. Anderson Meson Physics Facility in Los Alamos has been completed. And a search for the rare muon decays mu to e−gamma, to e−2gamma, and to 3e is ready to start taking data. (AIP)