98478755
Monitoring the parameters of a large size liquid Argon Time Projection Chamber using UV laser beams
This paper reports on 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 monitoring of the next generation large mass LAr TPCs [1]. The detector we have designed and tested allowed us also to measure the two-photon absorption cross-section (σex) of LAr with unprecedented accuracy and precision, appropriate for using the UV laser technique also for a quantitative calibration of the detector.
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.
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.
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.)
16952539
Variation of the Rate of Decay of Mesotrons with Momentum
In order to determine the dependence of the probability of decay on momentum, mesotrons with range between 196 and 311 g/cm' of lead and mesotrons with range larger than 311 g/cm' of lead were investigated separately. The softer group of mesotrons was found to disintegrate at a rate about three times faster than the more penetrating group, in agreement with the theoretical predictions based on the relativity change in rate of a moving clock. A new value of the proper lifetime of mesotrons of (2.4+0.3) &(10 ' sec. is determined, based upon measurements with particles with momentum of approximately 5 &&10' ev/c.
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.)
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.)
119999230
Early days in cosmic rays
Early in 1928, shortly after receiving my PhD at the University of Bologna, I was offered the position of assistant at the Physics Institute of the University of Florence. The Institute rose among olive trees, on the hill of Arcetri, a short distance from the villa where Galileo had spent the last years of his life as a political exile. The chair of physics was held by Professor Antonio Garbasso who, in earlier years, had done some creditable scientific work. But the first world war and subsequent events had diverted his interests toward politics. He was now a senator and the mayor of Florence. However, he still went to Arcetri three times a week to deliver his lectures, and he still had a strong desire to see the Institute, which he had built, become an important center of research.