13 research outputs found
Neutron background in large-scale xenon detectors for dark matter searches
Simulations of the neutron background for future large-scale particle dark
matter detectors are presented. Neutrons were generated in rock and detector
elements via spontaneous fission and (alpha,n) reactions, and by cosmic-ray
muons. The simulation techniques and results are discussed in the context of
the expected sensitivity of a generic liquid xenon dark matter detector.
Methods of neutron background suppression are investigated. A sensitivity of
pb to WIMP-nucleon interactions can be achieved by a
tonne-scale detector.Comment: 35 pages, 13 figures, 2 tables, accepted for publication in
Astroparticle Physic
First Results from the Heidelberg Dark Matter Search Experiment
The Heidelberg Dark Matter Search Experiment (HDMS) is a new ionization
Germanium experiment in a special design. Two concentric Ge crystals are housed
by one cryostat system, the outer detector acting as an effective shield
against multiple scattered photons for the inner crystal, which is the actual
dark matter target. We present first results after successfully running the
prototype detector for a period of about 15 months in the Gran Sasso
Underground Laboratory. We analyze the results in terms of limits on
WIMP-nucleon cross sections and present the status of the full scale
experiment, which will be installed in Gran Sasso in the course of this year.Comment: 11 pages, latex, 4 tables, 10 figures; submitted to Phys. Rev.
AnĂĄlise energĂ©tica em sistema de produção de suĂnos com aproveitamento dos desejos como biofertilizante em pastagem Energy analysis in a swine production system with use of manure as biofertilizer in pasture
O objetivo deste trabalho foi estimar a quantidade de energia para a produção de suĂnos, em ciclo completo, e o balanço energĂ©tico do sistema com reaproveitamento dos resĂduos gerados como biofertilizante, em ĂĄrea de pastagem, utilizando dados mĂ©dios de cinco ciclos, em granja comercial no municĂpio de Diamantina - MG. Quantificou-se o coeficiente energĂ©tico de cada componente envolvido no processo produtivo de suĂnos terminados, tratamento dos resĂduos e produção de pastagem de Brachiaria decumbens, nas formas de ração, trabalho humano, energia elĂ©trica, mĂĄquinas e equipamentos, combustĂveis e lubrificantes, instalaçÔes, produção de suĂnos vivos e produção de Brachiaria decumbens. A quantidade mĂ©dia de energia para produzir 1 kg de suĂno vivo foi de 53,35 MJ. De toda energia empregada no sistema, 76,03% (1.067.106,07 MJ) referem-se Ă s entradas e 23,97% (331.400 MJ) Ă s saĂdas, resultando em coeficiente de eficiĂȘncia energĂ©tica de 0,31. A energia transformada em suĂnos para abate correspondeu a 55,58% (184.200 MJ) das saĂdas, ao passo que a pastagem de Brachiaria decumbens assumiu o valor de 44,42% (147.200 MJ).<br>This work objective was to esteem the amount of energy employed in a complete cycle swine production and the energy balance of the system with utilization of the generated manure as biofertilizer in pasture area, by using five cycles' average data, in a commercial farm in Diamantina municipal district - MG Brazil. The energy coefficient of each involved component was quantified in the productive process of finished swine, residues treatment and Brachiaria decumbens pasture production, in the form of ration, human labor, electric power, machines and equipments, fuel and lubricants, buildings, finished swine production and Brachiaria decumbens production. The average quantity of energy to produce 1 kg of alive swine was of 53.35 MJ. Of total employed energy in the system 76.03% (1,067,106.07 MJ) refers to the inputs and 23.97% (331,400 MJ) refers to the outputs, resulting in an energy efficiency coefficient of 0.31. The energy converted in swine for abate corresponded to 55.58% (184,200 MJ) of the outputs, while the pasture of Brachiaria decumbens reached a value of 44.42% (147,200 MJ)