Neutron irradiation effect on SiPMs up to Φneq\Phi_{neq} = 5 ×\times 1014^{14} cm−2^{-2}

Silicon Photo-Multipliers (SiPM) are becoming the photo-detector of choice for increasingly more particle detection applications, from fundamental physics to medical and societal applications. One major consideration for their use at high-luminosity colliders is the radiation damage induced by hadrons, which leads to a dramatic increase of the dark count rate. KETEK SiPMs have been exposed to various fluences of reactor neutrons up to $\Phi_{neq}$ = 5$\times$10$^{14}$ cm$^{-2}$ (1 MeV equivalent neutrons). Results from the I-V, and C-V measurements for temperatures between $-$30$^\circ$C and $+$30$^\circ$C are presented. We propose a new method to quantify the effect of radiation damage on the SiPM performance. Using the measured dark current the single pixel occupation probability as a function of temperature and excess voltage is determined. From the pixel occupation probability the operating conditions for given requirements can be optimized. The method is qualitatively verified using current measurements with the SiPM illuminated by blue LED light

Design, development and evaluation of Stanford/Ames EVA prehensors

Space Station operations and maintenance are expected to make unprecedented demands on astronaut EVA. With Space Station expected to operate with an 8 to 10 psi atmosphere (4 psi for Shuttle operations), the effectivness of pressurized gloves is called into doubt at the same time that EVA activity levels are to be increased. To address the need for more frequent and complex EVA missions and also to extend the dexterity, duration, and safety of EVA astronauts, NASA Ames and Stanford University have an ongoing cooperative agreement to explore and compare alternatives. This is the final Stanford/Ames report on manually powered Prehensors, each of which consists of a shroud forming a pressure enclosure around the astronaut's hand, and a linkage system to transfer the motions and forces of the hand to mechanical digits attached to the shroud. All prehensors are intended for attachment to a standard wrist coupling, as found on the AX-5 hard suit prototype, so that realistic tests can be performed under normal and reduced gravity as simulated by water flotation

Design, development and evaluation of Stanford/Ames Extra-Vehicular Activity (EVA) prehensors

A summary is given of progress to date on work proposed in 1983 and continued in 1985, including design iterations on three different types of manually powered prehensors, construction of functional mockups of each and culminating in detailed drawings and specifications for suit-compatible sealed units for testing under realistic conditions

A New Modal Analysis Method to put Constraints on the Aqueous Alteration of CR Chondrites and Estimate the Unaltered CR Composition

CR carbonaceous chondrites are of the major interest since they contain one of the most primitive organic matters. However, aqueous alteration has more or less overprinted their original features in a way that needed to be assessed. That was done in the present study by comparing the mineralogy of the most altered CR1 chondrite, GRO 95577, to a less altered CR2, Renazzo. Their modal analyses were achieved thanks to a new method, based on X-ray elemental maps acquired on electron microprobe, and on IDL image treatment. It allowed the collection of new data on the composition of Renazzo and confirmed the classification of GRO 95577 as a CR1. New alteration products for CRs, vermiculite and clinochlore, were observed. The homogeneity of the Fe-poor clays in the CR1 and the distinctive matrix composition in the two chondrites suggest a wide-range of aqueous alteration on CRs. The preservation of the outlines of the chondrules in GRO 95577 and the elemental transfers of Al, Fe and Ca throughout the chondrule and of Fe and S from the matrix to the chondrule favor the idea of an asteroidal location of the aqueous alteration. From their mineralogical descriptions and modal abundances, the element repartitions in Renazzo and GRO 95577 were computed. It indicates a possible relationship between these two chondrites via an isochemical alteration process. Knowing the chemical reactions that occurred during the alteration, it was thus possible to decipher the mineralogical modal abundances in the unaltered CR body