272273
Further Measurements on the Disintegration Curve of Mesotrons
'HE authors of the present paper have recently described a method for the experimental determination of the disintegration curve of Tnesotrons and have given a preliminary account of the results obtained. ' The method has been since improved and a new and more extensive set of data has been taken. A summary of the riew results is presented here. The experimental arrangement, which is similar in principle to that used in the previous experiment, is schematically represented in Fig. 1. The three counters L are in parallel, and so are the four counters 8 and the five counters JI. Counters A, ~, A2, and 8 feed into the "time circuit" T; this circuit gives a pulse whose amplitude is a function of the time delay between a coincidence A &A2 and the subsequent pulse of 8. Counters L, A1, A~, 8, and M feed into an anticoincidence circuit C, which records the anticoincidences LA1A28 —2VI, i.e. , the coincidences between LA1A2 and 8 which are not accompanied by a pulse in lK The recording circuit R operates a pen writing instrument in such a way that the pulse from the time circuit is recorded only when it is accompanied by a pulse from the anticoincidence circuit. The events which one desires to record are of the following type. A mesotron traverses the counters L, A1, and A &, is stopped in the absorber A, and then disintegrates giving rise to an electron which discharges one of counters B.The amplitude of the pulse from the time circuit, as recorded by the pen writing instrument, gives a measure of the life span of the mesotron in the absorber. In addition to the records representing disintegration events, records will be obtained whenever
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.
124758213
The Variation of the Hard Component of Cosmic Rays With Height and the Disintegration of Mesotrons
120635227
Cosmic-Ray Theory
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.
50358222
The decay of 'mesotrons' (1939-1943), experimental particle physics in the age of innocence
An account is given of the experimental work carried out by the author and his associates during the years 1939 through 1943, which produced the first unambiguous evidence of the spontaneous decay of “mesotrons,” showed that this decay occurred according to an exponential law, as expected, and measured the mean life with a 3% accuracy. A by product of this work was a verification of the relativistic equation for the dilation of time intervals.
110883987
30 kV coaxial vacuum-tight feedthrough for operation at cryogenic temperatures
In this paper we describe the technology of building a vacuum-tight high voltage feedthrough which is able to operate at voltages up to 30 kV. The feedthrough has a coaxial structure with a grounded sheath which makes it capable to lead high voltage potentials into cryogenic liquids, without risk of surface discharges in the gas phase above the liquid level. The feedthrough is designed to be used in ionization detectors, based on liquefied noble gases, such as Argon or Xenon.
14164208
A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization
This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration play an important role. Results from the first measurements are presented together with some considerations and outlook.
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.
2310547
Study of ionization signals in a liquid Argon TPC doped with Nitrogen
In this paper we report on the evidence for ionization track signals from cosmic ray muons and Compton electrons in a Time Projection Chamber (TPC) filled with liquid Argon and doped with different fractions of Nitrogen. This study has been conducted in view of the possible use of liquid Argon/Nitrogen TPCs for the detection of gamma rays in the resonant band of the Nitrogen absorbtion 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.