Near threshold response of a wave shifted Cerenkov radiator to heavy ions

The response of Pilot 425 to heavy ions with energies less than 600 MeV/amu beta approximately 0.8 is examined both theoretically and experimentally. Measurements are presented from an experiment which employed a Ne-20 beam at many energies below 575 MeV/amu. The signal is assumed to come from three sources: (1) Cerenkov light from the heavy ion, (2) Cerenkov light from secondary electrons, and (3) scintillation of the radiator. It is found that the effective index of refraction is 1.518 and that scintillation is present at a level of approximately 2.7 percent of the Cerenkov signal for beta = 1 for Ne-20. The first of these values differs from values previously quoted in the literature

High resolution Cerenkov and range detectors for balloon-borne cosmic-ray experiment

A combination of an active Cerenkov detector and passive range detectors is proposed for the high resolution measurement of isotopic composition in the neighborhood of iron in the galactic cosmic rays. A large area (4,300 sq cm) Cerenkov counter and passive range detectors were tested. Tests with heavy ions (2.1 GeV/amu C-12, 289 MeV/amu Ar-40, and 594 MeV/amu Ne-20) revealed the spatial uniformity of response of the Cerenkov counter to be better than 1% peak-to-peak. Light collection efficiency is independent of projectile energy and incidence angle to within at least 0.5%. Passive Lexan track recorders to measure range in the presence of the nuclear interaction background which results from stopping particles through 0.9 interaction lengths of matter were also tested. It was found that nuclear interactions produce an effective range straggling distribution only approximately 75% wider than that expected from range straggling alone. The combination of these tested techniques makes possible high mass resolution in the neighborhood of iron

Performance of a large limited streamer tube cell in drift mode

The performance of a large (3x3 $cm^2$) streamer tube cell in drift mode is shown. The detector space resolution has been studied using cosmic muons crossing an high precision silicon telescope. The experimental results are compared with a GARFIELD simulation.Comment: 18 pages, 7 figures. Accepted by Nucl. Instr. and Methods

Background Rejection in the DMTPC Dark Matter Search Using Charge Signals

The Dark Matter Time Projection Chamber (DMTPC) collaboration is developing low-pressure gas TPC detectors for measuring WIMP-nucleon interactions. Optical readout with CCD cameras allows for the detection for the daily modulation in the direction of the dark matter wind, while several charge readout channels allow for the measurement of additional recoil properties. In this article, we show that the addition of the charge readout analysis to the CCD allows us too obtain a statistics-limited 90% C.L. upper limit on the $e^-$ rejection factor of $5.6\times10^{-6}$ for recoils with energies between 40 and 200 keV$_{\mathrm{ee}}$. In addition, requiring coincidence between charge signals and light in the CCD reduces CCD-specific backgrounds by more than two orders of magnitude.Comment: 8 pages, 6 figures. For proceedings of DPF 2011 conferenc

Search for exotic contributions to atmospheric neutrino oscillations

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant effect. The data disfavor these possibilities even at a sub-dominant level; stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter $|\Delta v| < 6 \times 10^{-24}$ at $\sin 2{\theta}_v$ = 0 and $|\Delta v| < 2.5 \div 5 \times 10^{-26}$ at $\sin 2{\theta}_v$ = $\pm$1. The limits can be re-interpreted as bounds on the Equivalence Principle violation parameters.Comment: Presented at the 29th I.C.R.C., Pune, India (2005

Search for a Lorentz invariance violation in atmospheric neutrino oscillations using MACRO data

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of special relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of nu_mu nu_tau transitions. The data disfavour these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameters. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.Comment: 8 pages, 5 EPS figures, uses article.sty. Invited talk at C2CR 2005, From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 September 200

Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data

Neutrino-induced upward-going muons in MACRO have been analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of nu_mu -> nu_tau transitions. The data disfavor these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter |Delta v| < 6 * 10^(-24) at sin2theta_v = 0 and |Delta v| < 2.5--5 * 10^(-26) at sin2theta_v = +/-1. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.Comment: 8 pages, 2 figures, submitted to Physics Letters