4,051 research outputs found
Space Radiation and Impact on Instrumentation Technologies
Understanding the interactions of the Sun, Earth and other natural and man-made objects in the solar system with the space radiation environment is crucial for improving activities of humans on Earth and in space. An important component of understanding these interactions is their effects on the instrumentation required in the exploration of air and space. NASA's Glenn Research Center (GRC) fills the role of developing supporting technologies to enable improved instruments for space science missions, as well as improved instruments for aeronautics and ground-based applications. In this review, the space radiation environment and its effects are outlined, as well the impact it has on instrumentation and the technology that GRC is developing to improve performance for space science
Performance evaluation of novel square-bordered position-sensitive silicon detectors with four-corner readout
We report on a recently developed novel type of large area (62 mm x 62 mm)
position sensitive silicon detector with four-corner readout. It consists of a
square-shaped ion-implanted resistive anode framed by additional
low-resistivity strips with resistances smaller than the anode surface
resistance by a factor of 2. The detector position linearity, position
resolution, and energy resolution were measured with alpha-particles and heavy
ions. In-beam experimental results reveal a position resolution below 1 mm
(FWHM) and a very good non-linearity of less than 1% (rms). The energy
resolution determined from 228Th alpha source measurements is around 2% (FWHM).Comment: 13 pages, 10 figures, submitted to Nucl. Instr. and Meth.
Effects of space radiation on electronic microcircuits
The single event effects or phenomena (SEP), which so far have been observed as events falling on one or another of the SE classes: Single Event Upset (SEU), Single Event Latchup (SEL) and Single Event Burnout (SEB), are examined. Single event upset is defined as a lasting, reversible change in the state of a multistable (usually bistable) electronic circuit such as a flip-flop or latch. In a computer memory, SEUs manifest themselves as unexplained bit flips. Since latchup is in general caused by a single event of short duration, the single event part of the SEL term is superfluous. Nevertheless, it is used customarily to differentiate latchup due to a single heavy charged particle striking a sensitive cell from more ordinary kinds of latchup. Single event burnout (SEB) refers usually to total instantaneous failure of a power FET when struck by a single particle, with the device shorting out the power supply. An unforeseen failure of these kinds can be catastrophic to a space mission, and the possibilities are discussed
In-beam internal conversion electron spectroscopy with the SPICE detector
The SPectrometer for Internal Conversion Electrons (SPICE) has been
commissioned for use in conjunction with the TIGRESS -ray spectrometer
at TRIUMF's ISAC-II facility. SPICE features a permanent rare-earth magnetic
lens to collect and direct internal conversion electrons emitted from nuclear
reactions to a thick, highly segmented, lithium-drifted silicon detector. This
arrangement, combined with TIGRESS, enables in-beam -ray and internal
conversion electron spectroscopy to be performed with stable and radioactive
ion beams. Technical aspects of the device, capabilities, and initial
performance are presented
Irradiation of silicon particle detectors with MeV-protons
Silicon particle detectors are used in several applications and will clearly require better hardness against particle radiation in the future large scale experiments than can be provided today. To achieve this goal, more irradiation studies with defect generating bombarding particles are needed. Protons can be considered as important bombarding species, although neutrons and electrons are perhaps the most widely used particles in such irradiation studies. Protons provide unique possibilities, as their defect production rates are clearly higher than those of neutrons and electrons, and, their damage creation in silicon is most similar to the that of pions.
This thesis explores the development and testing of an irradiation facility that provides the cooling of the detector and on-line electrical characterisation, such as current-voltage (IV) and capacitance-voltage (CV) measurements. This irradiation facility, which employs a 5-MV tandem accelerator, appears to function well, but some disadvantageous limitations are related to MeV-proton irradiation of silicon particle detectors.
Typically, detectors are in non-operational mode during irradiation (i.e., without the applied bias voltage). However, in real experiments the detectors are biased; the ionising proton generates electron-hole pairs, and a rise in rate of proton flux may cause the detector to breakdown. This limits the proton flux for the irradiation of biased detectors. In this work, it is shown that, if detectors are irradiated and kept operational, the electric field decreases the introduction rate of negative space-charges and current-related damage. The effects of various particles with different energies are scaled to each others by the non-ionising energy loss (NIEL) hypothesis. The type of defects induced by irradiation depends on the energy used, and this thesis also discusses the minimum proton energy required at which the NIEL-scaling is valid.Piipohjaisia hiukkasilmaisimia käytetään laajalti niin ilmailussa, avaruustekniikassa kuin suurenergiafysiikan kokeissa. Piipohjainen hiukkasilmaisin on toiminnaltaan estosuuntaan kytketty diodi ja säteilyn, joka voi olla joko hiukkas- tai sähkömagneettista säteilyä, aiheuttamat vauriot vaikuttavat ilmaisimen sähköisiin ominaisuuksiin (virta-jännite, kapasitanssi-jännite) heikentäen sen toimintakykyä. Tulevaisuudessa ilmaisimilta tullaankin vaatimaan nykyistä suurempaa säteilynkestoa. Säteilynkestotutkimuksissa säteilyttävänä hiukkasena on usein neutroni, protoni tai elektroni. Suurenergiafysiikan kannalta protonisäteilytykset ovat erityisen tärkeitä, sillä niiden aiheuttamat vauriot ilmaisimessa ovat samankaltaisia kuin pionien aiheuttamat. Lisäksi MeV-protonien aiheuttama vauriomäärä on selvästi suurempi kuin neutroneilla ja elektroneilla lyhentäen näin säteilytysaikoja.
Ilmaisimen toimintakykyä voidaan parantaa jäähdytyksellä. Tavallisesti säteilytykset tehdään kuitenkin huoneenlämmössä ja ilmaisin ei ole toiminnassa säteilytyksen aikana. Tämä väitöstutkimus keskittyy matalan lämpötilan säteilytyslaitteiston, jossa ilmaisimin pidetään toiminnassa ja sen sähköisiä ominaisuuksia mitataan myös säteilytyksen aikana, kehitykseen ja testaukseen. Laitteisto, joka on toteutettu Helsingin yliopiston 5 MV tandemkiihdyttimen yhteyteen, on testattu ja todettu toimivaksi tietyin rajoituksin, jotka liittyvät MeV-protonisäteilytyksiin
Detection
This review on second- and third-generation multidetectors devoted to heavy-ion collisions aims to cover the last twenty years. The presented list of devices is not exhaustive but regroups most of the techniques used during this period for nuclear reactions at intermediate energy (≈ 10A MeV to 1A GeV), both for charged-particle and neutron detection. The main part will be devoted to 4π multidetectors, projectile decay fragmentation, high-resolution magnetic spectrometers, auxiliary detectors and neutron detection. The last part will present the progress in electronics and detection in view of the construction of future-generation detectors
Discovery of the Isotopes with 11 <= Z <= 19
A total of 194 isotopes with 11 Z 19 have been identified to
date. The discovery of these isotopes which includes the observation of unbound
nuclei, is discussed. For each isotope a brief summary of the first refereed
publication, including the production and identification method, is presented.Comment: to be pubslihed in At. Data Nucl. Data Table
Population of low-lying levels in the one-neutron halo nucleus 11Be via the neutron transfer reaction 10Be(d,p)
Historically, measurements of differential cross-sections for the neutron transfer reaction (d, p) on stable targets have been an important tool for extracting spectroscopic information. In particular, it is possible to make orbital angular momentum assignments and extract spectroscopic factors for ground states and excited states by comparing measurements to cross sections calculated for pure single-particle states. In recent years, the advent of rare isotope beams have made it possible to apply this method to increasingly exotic nuclei. As nucleon separation energies decrease along the path to the proton and neutron drip lines, many new reaction channels are opened. Out of the open channels arise complications for theoretical calculations that are not well understood. The archetypal one neutron halo nucleus 11Be has been an important test case for theoretical studies, being within the reach of ab initio theory and relatively near the valley of particle stability while possessing several exotic properties. Although its ground state properties have been studied thoroughly, spectroscopic factors for the first excited state are not well understood. Additionally, little is known about the low-lying resonances. The current study has been performed to provide an extensive data set for the reaction 10Be(d, p) in inverse kinematics, including elastic and inelastic scattering channels important for optical model parameterizations. Differential cross-sections have been measured at equivalent deuteron beam energies of 12, 15, 18, and 21.4 MeV. Results are compared to previous measurements in inverse kinematics at 12 and 25 MeV. The data are also used to evaluate the Distorted Wave Born Approximation and Adiabatic Distorted Wave Approximation methods for cross section calculations and spectroscopic factors are extracted in each case
Characterization of a Boron Carbide Heterojunction Neutron Detector
New methods for neutron detection have become an important area of research in support of national security objectives. In support of this effort, p-type B5C on n-type Si heterojunction diodes have been built and tested. This research sought to optimize the boron carbide (BC) diode by coupling the nuclear physics modeling capability of GEANT4 and TRIM with the semiconductor device simulation tools. Through an iterative modeling process of controllable parameters, optimal device construction was determined such detection efficiency and charge collection were optimized. This allows an estimation of expected charge collection and efficiency given a set of operating parameters that include: silicon resistivity, BC resistivity, BC thickness, silicon thickness, applied bias, and collection contact. Charge collection was maximized with high bias operation of thin BC layers on thin silicon substrates of low resistivity (\u3c10 Ω-cm), while the capture efficiency was maximized for thicker BC layers.
Additionally, the effects of neutron damage on BC diodes were studied to determine damage thresholds and resulting device performance and lifetime. The major limitation found for device performance was the increase in the leakage current (~340% at a thermal fluence of 9.7x1013 n cm-2) in the 8k Ω-cm diode. Type inversion was not measured at the total fluence levels achieved, but the 8k Ω-cm diode effective carrier concentrations (Neff) decreased by 30% at a total thermal fluence of 7.5x1013 n cm-2 (1x1013 1 MeV neutron equivalent). For the same irradiation conditions, the 20k Ω-cm diode Neff decreased by 57%. These results indicate that the hardness of the diodes can be improved with low resistivity silicon substrates
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