RESUMO
The PICASSO experiment investigates the presence and nature of dark matter in the Universe. The experiment is based on the detection of acoustic signals generated in explosive phase transitions induced by dark matter particles. This technique is an alternative more traditional detection technique like scintillation and ionisation, which are largely employed for dark matter search. One of the main advantages of this technique, besides its sensitivity to very low nuclear recoil energies (few keV), is its excellent background suppression features. A pilot experiment consisting of six superheated droplet detectors (40 g of active mass) is presently taking data at the Sudbury Neutrino Observatory (SNO) at a depth of 2000 m. We discuss the operation, calibration and data acquisition of the experiment and also the ongoing work to increase the sensitivity and the active mass of the detectors.
Assuntos
Radiação Cósmica , Meio Ambiente Extraterreno , Temperatura Alta , Microbolhas , Dosimetria Termoluminescente/instrumentação , Relação Dose-Resposta à Radiação , Desenho de Equipamento , Análise de Falha de Equipamento , Géis/química , Géis/efeitos da radiação , Teste de Materiais , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Propriedades de Superfície , Dosimetria Termoluminescente/métodosRESUMO
The PICASSO project is a cold dark matter (CDM) search experiment relying on the superheated droplet technique. The detectors use superheated freon liquid droplets (active material) dispersed and trapped in a polymerised gel. This detection technique is based on the phase transition of superheated droplets at about room temperature and ambient pressure. The phase transition is induced by nuclear recoils when an atomic nucleus in the droplets interacts with incoming subatomic particles. This includes CDM particles candidate as the neutralino (a yet-to-discover particle predicted in extensions of the standard model of particle physics). Simulations performed to understand the detector response to neutrons and alpha particles are presented along with corresponding data obtained at the Montreal Laboratory.