A study of signals originating near the lithium-diffused n+ contact of p-type point contact (PPC) high purity germanium detectors (HPGe) is presented. The transition region between the active ...germanium and the fully dead layer of the n+ contact is examined. Energy depositions in this transition region are shown to result in partial charge collection. This provides a mechanism for events with a well defined energy to contribute to the continuum of the energy spectrum at lower energies. A novel technique to quantify the contribution from this source of background is introduced. Experiments that operate germanium detectors with a very low energy threshold may benefit from the methods presented herein.
The time profiles of Cu, Sn, and Ni ions extracted from a hot-cavity resonant ionization laser ion source are investigated. The ions are produced in the ion source by three-photon resonant ionization ...with pulsed Ti:Sapphire lasers. Measurements show that the time spread of these ions generated within laser pulses of about 30
ns duration could be larger than 100
μs when the ions are extracted from the ion source. A one-dimensional ion-transport model using the Monte Carlo method is developed to simulate the time dependence of the ion pulses. The prediction of the model agrees reasonably well with the experimental data. To reproduce the observed ion time profiles, we find it necessary to postulate that ion-wall collisions are suppressed inside the ion source by an undetermined ion confinement mechanism and that a substantial fraction of the extracted ions are generated in the vapor-transfer tube rather than the hot cavity. Three-dimensional modeling will be necessary to understand the strong reduction in losses expected from ion-wall collisions which we interpret as evidence for confinement.
Development of a plasma panel muon detector Levin, D.S.; Ball, R.; Beene, J.R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2011, Letnik:
652, Številka:
1
Journal Article
Recenzirano
A radiation detector technology based on plasma display panels (PDPs), the underlying engine of panel plasma television displays, is being investigated. Emerging from this well-established television ...technology is the Plasma Panel Sensor (PPS), a novel variant of the micro-pattern radiation detector. The PPS is fundamentally a fast, high-resolution detector comprised of an array of plasma discharge cells, operating in a hermetically sealed gas mixture. We report on the PPS development effort, including proof-of-principle results of laboratory signal observations.
Development of a plasma panel radiation detector Ball, R.; Beene, J.R.; Ben-Moshe, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2014, Letnik:
764
Journal Article
Recenzirano
Odprti dostop
This article reports on the development and experimental results of commercial plasma display panels adapted for their potential use as micropattern gas radiation detectors. The plasma panel sensor ...(PPS) design and materials include glass substrates, metal electrodes and inert gas mixtures which provide a physically robust, hermetically sealed device. Plasma display panels used as detectors were tested with cosmic ray muons, beta rays and gamma rays, protons, and thermal neutrons. The results demonstrated rise times and time resolution of a few nanoseconds, as well as sub-millimeter spatial resolution compatible with the pixel pitch.
The Majorana Demonstrator will search for the neutrinoless double–beta decay (0vββ) of the 76Ge isotope with a mixed array of enriched and natural germanium detectors. The observation of this rare ...decay would indicate the neutrino is its own anti–particle, demonstrate that lepton number is not conserved, and provide information on the absolute mass–scale of the neutrino. The Demonstrator is being assembled at the 4850 foot level of the Sanford Underground Research Facility in Lead, South Dakota. The array will be contained in a low–background environment and surrounded by passive and active shielding. The goals for the Demonstrator are: demonstrating a background rate less than 3 t−1 y−1 in the 4 keV region of interest (ROI) surrounding the 2039 keV 76Ge endpoint energy; establishing the technology required to build a tonne–scale germanium based double–beta decay experiment; testing the recent claim of observation of 0vββ 1; and performing a direct search for light WIMPs (3-10 GeV/c2).
Helium jet ion source in FRIB era Das, J J; Carter, H K; Beene, J R ...
Journal of physics. Conference series,
01/2013, Letnik:
420, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Gas stopping of reaction products has a key feature, fixed holdup time independent of element, making it possible to provide ion beams of essentially all element. Two classes of gas stopping have ...been developed over the last 40+ years, broadly classified as He Jet and Ion guide. A primary difference between these two techniques is the physical separation of the stopping cell and the ionization cell in the He Jet technique. In this paper we point out two applications of current interest where this physical separation is crucial: 1) ionization (ion beam intensity) is independent of primary beam intensity and 2) multiuser capability for accelerator facilities. Specific examples will be described.
As one step in the ion source development for the Rare Isotope Accelerator, a hot-cavity laser ion source using an all-solid-state titanium–sapphire laser system has been tested at the Holifield ...Radioactive Ion Beam Facility. Resonance ionization of stable isotopes of Sn, Ge and Ni has been studied in a Ta hot cavity. Efficient three step resonant ionization schemes applying frequency tripling for the first excitation step and using auto-ionizing or atomic Rydberg states in the ionizing step have been identified for all three elements, resulting in laser ion beams of typically around 100
nA. By saturating most of the optical excitation steps involved, ionization efficiencies of 22%, 3.3% and 2.7% have been measured for Sn, Ge and Ni, respectively.
The 2+2 state in 132Te is identified as the one-phonon MSS in a projectile Coulomb excitation experiment presenting a firm example of a MSS in unstable, neutron rich nuclei. The results of ...shell-model calculations based on the low-momentum interaction Vlow−k are in good agreement with experiment demonstrating, the ability of the effective shell-model interaction to produce states of mixed symmetry character.
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