Status of the ANAIS experiment at Canfranc

Transcription

1 Status of the ANAIS experiment at Canfranc J. Amaré, B. Beltrán, J. M. Carmona, S. Cebrián, E. García, H. Gómez, G. Luzón,, J. Morales, A. Ortiz de Solórzano, C. Pobes, J. Puimedón, A. Rodriguez, J. Ruz, M.L. Sarsa, L. Torres, J. A. Villar - Objective - Previous results - Description of the experiment - Work in progress IDM 2004 Edinburgh Conference.

2 OBJECTIVE Dark matter search Dark energy 73% Ω ~ 1 New observations Distant SN Ia CMB Anisotropies WMAP Jupiters, Brown dwarfs, Black holes, MACHOs, Baryonic 4% Visible < 1% Stars, galaxies, non baryonic Dark Matter 23 % Neutrinos, WIMP s, Axions, Others

3 OBJECTIVE Detection of WIMP s Indirect: annihilation Direct: Methods: nuclear recoil induced by the elastic scattering off target nuclei Energy deposit due to WIMP - Nucleus elastic scattering appears as Heat Ionization Scintillation 1. Derivation of exclusion plots σ p (m): 2. Looking for distinctive signals

4 OBJECTIVE ANAIS: Annual modulation with NaI s Direct detection of WIMP s With NaI(Tl) scintillators Looking for a distinctive signature: ANNUAL MODULATION: Cos-like signal (1 year period, max 2nd June) Modulation amplitude ~(5%-7%) Only in a low energy window Incident WIMP Detector-Target Nuclear recoil α = 30º Scattered WIMP light light v r = 232 km/s v orbital = 30 km/s

5 PREVIOUS RESULTS Phys. Rev. D 56 (1997) : NaI32 (32 kg NaI), pioneer experiment looking for the annual modulation effect at LSC Nucl. Phys. B (Proc. Suppl.)114 (2003) : ANAIS Prototype I (10,7 kg NaI, LSC) Threshold: ~ 4 kev Background: 1.2 c/kev/kg/day in 4-10 kev

6 PREVIOUS RESULTS ANAIS Prototype I: Exclusions SI : σ n (pb) I Na NaI Exposure: kg day S.I., 90% C. L m W (GeV) I Na NaI SD : σ n (pb) S.D., 90% C. L m W (GeV)

7 PREVIOUS RESULTS DAMA results Exposure kg day. Energy interval 2-6 kev * Residuals (cpd//kg/kev) Time (day) A Cos(ω(t t 0 )) * Riv. N. Cim. 26 n.1 (2003) 1-73 A = ( ± ) c/day/kg/kev, T = 2π/ω = (1.00 ± 0.01) years t 0 = (140 ± 22) days

8 DESCRIPTION OF THE EXPERIMENT ANAIS: description of the experiment 10 x 10.7 kg NaI, Underground since cm neutron shielding Active vetos To be installed At the new Canfranc Underground Laboratory in cm Roman lead 20 cm lead PVC box 2 mm Cd

9 DESCRIPTION OF THE EXPERIMENT DATA ACQUISITION SYSTEM CAMAC and NIM components. PCI bus. Multiprocessor PC under Linux O.S. with Real-time module (RTAI). PSD: Digitizer up to 2 Gs/s. 500MHz analog bandwidth. SLOW CONTROL: Temperature (inner & outer) HV stability Radon level N 2 flux & pressure etc

10 WORK IN PROGRESS Prototype II: Threshold and background reduction Experimental Cu-box Light guides 2 ultra-low background PMT Teflon bank

11 WORK IN PROGRESS Light collection improvement Experimental set-up (LED + Cu-box + light guides + PMT) MC Simulations with OPTICS code (*) adapted (Simulation of geometry and materials) Methacrylate guides NaI NaI Teflon difuser * Computer Physics Comunications, 0 (2000), 1-26

12 WORK IN PROGRESS Light collection improvement Experimental set-up (LED + Cu-box + light guides + PMT) MC Simulations with OPTICS code (*) adapted (Simulation of geometry and materials) R=0.9, L=100cm R=0.99,L=300cm % Collected light (2 PMT) Light guide length (cm)

13 WORK IN PROGRESS Light collection improvement Experimental set-up (LED + Cu-box + light guides + PMT) MC Simulations with OPTICS code (*) adapted (Simulation of geometry and materials) % collected light in one PMT dt between PMT pulses % collected light in one PMT Position in Z axis (cm) dt between PMT pulses (ns)

14 WORK IN PROGRESS Light collection improvement Experimental set-up (LED + Cu-box + light guides + PMT) MC Simulations with OPTICS code (*) adapted (Simulation of geometry and materials) % collected light Light guide length 2 cm diffuser 2cm reflectant 2 cm Reflectivity diffuser 10 cm reflectant 10 cm % collected light Light guide length 10 cm

15 WORK IN PROGRESS α / β+γ discrimination in the high energy region to determine α contamination. β+γ α R α 3 mbq/kg τ decay (4ns/point)

16 WORK IN PROGRESS α / β+γ discrimination in the high energy region to determine 210 Pb contamination. Neutron calibration for PSD analysis. MC Simulations (GEANT4) to find best shielding & crystal size. lead NaI 80cm 3 Am-Be source polyethylene

17 WORK IN PROGRESS α / β+γ discrimination in the high energy region to determine 210 Pb contamination. Neutron calibration for PSD analysis. MC Simulations (GEANT4) to find best shielding & crystal size. Study of dark pulses from the PMT and determination of the number of photoelectrons/kev.

18 WORK IN PROGRESS First results on next Taup 2005