A fifteen inch magnetic spectrometer using its fringing field to achieve double focusing has been developed and made ready for experimental work. Its power supply delivers continuously variable currents from 0-100 amperes. The current is stable to one part in ten thousand, being regulated by a transistor amplifier which drives a bank of parallel output power transistors. Interlocks are provided to protect the components against foreseeable hazards. The vacuum and detecting systems are complete, and the spectrometer has been tested with various alpha sources. The best resolution obtained was .57 per cent, but there should be much better resolving power inherent in the spectrometer, unrevealed because the sources used were fairly large. A resolution measurement of scattered protons when the beam from the Van de Graaff is put in to the spectrometer should determine the resolution more accurately. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Call number: LD2668 .T4 1952 K7 / Master of Science

Thesis (M.S.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references (leaves 44-48). Online version available on the World Wide Web.

A study has been made of the external conversion spectrum of gamma-rays of less than 200 kev. A set of semi-empirical curves relating the photoelectric peak height to the gamma-ray intensity has been established using antimony radiators. These results will be discussed. A method of preparing thin beta sources will also be described. / Thesis / Master of Science (MSc)

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The coincident measurement of gamma-rays originating from nuclei excited in light-ion reactions and scattered alpha-particles presents interesting opportunities to characterize the decay path for low multi-polarity nuclear excitations. This coincident measurement at θlab = 0◦ was shown to be a powerful tool for the spectroscopy of isoscalar E1 transitions, being selective to distinct modes of bulk nuclear motions. Aided with the high resolution capabilities provided by the HPGe Clover detectors as well as the K600 magnetic spectrometer for both γ and charged particle detection, these experiments are motivated by the need to investigate E1 strength in stable nuclei around the particle emission threshold, more commonly referred to as the Pygmy Dipole Resonance (PDR). However, due to our detector configuration we find that higher effi- ciency detectors offer a better overall functionality in these α − γ coincidence measurements which specifically suffer from low statistics. The feasibility of the (α, α 0γ) reaction using high resolution Clover detectors and the high efficiency HAGAR detector is characterized through their effi- ciency to detect γ rays in coincidence with the K600 magnetic spectrometer at θlab = 0◦ . Through the construction of Eγ − EX coincidence matrices, decay transitions of closely lying nuclear excitations can be studied on a stateby-state basis. The result is a quantified representation of γ yield, of which optimization is the key focus in order to extract meaningful nuclear structure information. / AFRIKAANSE OPSOMMING: Die samevallende meting van gammastrale van kerne opgewek in die lig-ion reaksies en verspreide alfa-deeljties, bied interessante geleenthede aan om die verval pad vir lae multi-polariteit kern opwekkings te karakteriseer. Hierdie samevallende meting by θlab = 0◦ was getoon om ‘n kragtige instrument vir die spektroskopie van isoscalar E1 oorgange te wees, as gevolg van die vermoë om selektief te onderskei tussen modes van kollektiewe kern ossillasies. Aangehelp met die hoë resolusie moontlikhede wat deur die HPGe Clover detektors asook die K600 magnetiese spektrometer vir beide γ en gelaaide deeltjie opsporing, hierdie eksperimente is gemotiveer deur die behoefte om E1 krag te ondersoek in stabiele kerne rondom die deeltjie emissie drumpel, meer algemeen na verwys as die Pygmy Dipool Resonansie (PDR). Maar as gevolg van die detektor opset, vind ons dat ’n hoër doeltreffendheid detector ’n beter algehele funksionaliteit aanbied wat in hierdie samevallende metings veral belangrik is weens lae statistiek. Die haalbaarheid van die reaksie wat gebruik maak van hoë resolusie Clover detektors en die hoë doeltreffendheid HAGAR detektor word gekenmerk deur hul doeltreffendheid om gammastrale optespoor in toeval met die K600 magnetiese spektrometer by θlab = 0◦ . Deur die konstruksie van toeval Eγ − EX matrikse, verval oorgange van kern opwekkings kan op ’n staat-by-staat basis bestudeer word. Die resultaat is ’n gekwantifiseerde verteenwoordiging van γ opbrengs, waarvan optimalisering die sleutel fokus is om betekenisvolle kernstruktuur inligting te kan onttrek

Thesis. 1976. Ph.D. cn--Massachusetts Institute of Technology. Dept of Physics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. Vita. / Includes bibliographical references. / Ph.D.cn

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The optical design of the TRIUMF Second Arm Spectrometer (SASP) has been completed and the engineering design started. The effects of the dipole shape and field clamps on the aperture fringe fields were studied. It was determined that a field clamp would be necessary to achieve the field specifications over the desired range of dipole excitations. A specification of the dipole pole edges and field clamps for the SASP is made. A Monte Carlo simulator for the SASP was written. During the design this was used to study the profiles of rays passing through the SASP. These profiles were used in determining the positioning of the dipole vacuum boxes and the SASP detector arrays. The simulator is intended to assess experimental arrangements of the SASP. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

L'expérience AMS-02 est un détecteur de particules installé sur la station spatiale internationale (ISS) depuis mai 2011, date à partir de laquelle il mesure les caractéristiques des rayons cosmiques afin d'apporter des réponses aux problématiques soulevées par la physique des astroparticules depuis quelques décennies, en particulier l'étude indirecte de la matière sombre et la recherche d'antimatière. Les aspects phénoménologiques de la physique des rayons cosmiques sont revus dans la première partie. Une deuxième décrit les performances en vol des différents sous-détecteurs d'AMS-02, en particulier du calorimètre électromagnétique. Il est montré, en utilisant les particules au minimum d'ionisation (MIPs), qui constituent l'essentiel du rayonnement cosmique, que le calorimètre fonctionne comme prévu, et que l'on retrouve les mêmes performances qu'au sol. Cette étude est utilisée pour suivre au cours du temps l'évolution des performances du détecteur. Elle permet également de développer un estimateur de charge pour les noyaux utilisant le calorimètre. Une troisième et dernière partie s'attache enfin à déterminer le rapport positronique. La principale difficulté de cette mesure est d'identifier les positons en rejetant les protons grâce aux caractéristiques des gerbes dans la calorimètre. Après avoir défini des variables pertinentes pour cette séparation, nous construisons un estimateur via une analyse multivariée, en nous appuyant sur des simulations Monte-Carlo d'électrons pour les plus hautes énergies. Au-delà de 100 GeV, nous obtenons un taux de réjection de l'ordre de 10 000 pour 90% d'efficacité. Après avoir estimé la confusion de charge, cet estimateur nous permet finalement, de déterminer le rapport positronique pour les données acquises pendant les 18 premiers mois et pour des énergies allant de 1.5 à 350 GeV. / The AMS-02 experiment is a particle detector installed on the International Space Station (ISS) since May 2011, which measures the characteristics of the cosmic rays to bring answers to the problematics risen by the astroparticle physics since a few decades, in particular the study of dark matter and the search of antimatter. The phenomenological aspects of the physics of cosmic rays are reviewed in a first part. A second one describes the in-flight performances of the different subdetectors of AMS-02, in particular the electromagnetic calorimeter. It is shown, using particles at the ionizing minimum (MIPs), accounting for the main part of cosmic rays, that the calorimeter works as expected, and we find the same performances as on ground. This study is used to follow in time the evolution of the detector performances. It also allows to develop a charge estimator for the nuclei using the calorimeter. A third and final part, deals with the determination of the positronic fraction. The main difficulty of this measurement is to identify the positrons by rejecting the protons thanks to the characteristics of the showers in the calorimeter. After having defined variables relevant for this separation, we build an estimator using a multivariate analysis and Monte-Carlo simulations of electrons for the higher energies. Above 100 GeV, we obtain a rejection factor of about 10 000 at a 90% efficiency. After having estimated the charge confusion, this estimator, finally, allows us to determine the positronic ratio for the first 18 months of data and energies ranging from 1.5 to 350 GeV.