118548096
Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber
This paper reports on laser-induced multiphoton ionization at 266?nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: ?ex=(1.24?0.10stat?0.30syst)?10? 56?cm4?s? 1.
122307837
First measurements with ARGONTUBE, a 5m long drift Liquid Argon TPC
Abstract The Liquid Argon Time Projection Chamber (LAr TPC) technique is a promising technology for future neutrino detectors. At LHEP of the University of Bern (Switzerland), an R&D program towards large detectors are on-going. The main goal is to show the feasibility of long drift paths over many meters. Therefore, a liquid Argon TPC with 5 m of drift distance was constructed. Many other aspects of the liquid Argon TPC technology are also investigated, such as a new device to generate high voltage in liquid Argon (Greinacher circuit), a recirculation filtering system and the multi-photon ionization of liquid Argon with a UV laser. Two detectors are built: a medium size prototype for specific detector technology studies, and ARGONTUBE, a 5 m long device.
119265780
Ionization signals from electrons and alpha-particles in mixtures of liquid Argon and Nitrogen – perspectives on protons for Gamma Resonant Nuclear Absorption applications
In this paper we report on a detailed study of ionization signals produced by Compton electrons and alpha-particles in a Time Projection Chamber (TPC) filled with different mixtures of liquid Argon and Nitrogen. The measurements were carried out with Nitrogen concentrations up to 15% and a drift electric field in the range 0-50 kV/cm. A prediction for proton ionization signals is made by means of interpolation. This study has been conducted in view of the possible use of liquid Ar−N2 TPCs for the detection of gamma-rays in the resonant band of the Nitrogen absorption spectrum, a promising technology for security and medical applications.
120791125
Extremely Energetic Cosmic-Ray Event
An energetic cosmic ray event was analyzed using a a. The date of the event, though unspecified, was between Sept., 1959 and May, 1960. The event was recorded at the M.I.T. stution near Albuquerque. The shower center, radius, axis direction, composition, and arrival times at various counters are given. A model for the event is suggested. (T.F.H.)
122928206
ISOTROPY OF COSMIC RADIATION
Cosmic radiation data obtained at the Mass. Inst. of Tech. Volcano Ranch station in 1960 to 1961 were compared with that taken in 1959 to 1960 at the same location. The 1960 to 1961 data were obtained after the area of the array was increased by a factor of four and therefore have 3 times the statistical weight of the 1959 to 1960 data. An isotropic distribution in the direction of arrival of primary particles at about 10/sup 18/ ev is indicated. No conclusive evidence for existence or non-existence of anisotropies was found. (L.N.N.)
197448895
ENERGY SPECTRUM AND STRUCTURE OF LARGE AIR SHOWERS
Nineteen 3.3-m/sup 2/ plastic scintillation detectors in a hexagonal array covering 2 km/sup 2/ were used in this study. Methods of recording and analyzing data are discussed, and results are presented on the following: lateral distribution of particle density, the proportion of penetrating particles, variation of shower intensity and shower size with atmospheric depth, the primary cosmic ray energy spectrum, isotropy of primary cosmic radiation, and the largest shower recorded. (A.G.W.)
124758213
The Variation of the Hard Component of Cosmic Rays With Height and the Disintegration of Mesotrons
122227593
Evidence for x Rays From Sources Outside the Solar System
Data from an Aerobee rocket carrying three large-area geiger counters have revealed a considerable flux of radiation in the night sky. Analysis of these data indicates the bulk of the radiation is soft x rays from sources outside the solar system. Synchrotron radiation by cosmic electrons is a possible mechanism for the production of these x rays. Ordinary stellar sources could also contribute a considerable fraction of the observed radiation. (H.D.R.)