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Cryogenic particle detection at the Canfranc Underground Laboratory. ROSEBUD Collaboration UNIZAR - IAS. First International Workshop for the Design of the ANDES Underground Laboratory Centro Atómico Constituyentes Buenos Aires, Argentina 11-14 April, 2011. Outline.
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Cryogenic particle detection at the Canfranc Underground Laboratory ROSEBUD Collaboration UNIZAR - IAS First International Workshop for the Design of the ANDES Underground Laboratory Centro Atómico ConstituyentesBuenos Aires, Argentina11-14 April, 2011
Outline • The ROSEBUD Collaboration • The scintillating bolometer • Particle discrimination capability • Experimental set-up in the old LSC facilities • Main results: Light & heat response to different particles WIMP search prototypes Gamma and neutron spectroscopy • ROSEBUD in the new LSC facilities • EURECA
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
Canfranc Underground Laboratory (LSC) Universidad de Zaragoza UNIZAR (Spain) Institut d’Astrophysique Spatiale IAS (Orsay, France) ROSEBUD Collaboration(Rare Objects SEarch with Bolometers UndergrounD) N. Coron,C. Cuesta, E. García, C. Ginestra,J. Gironnet, P. de Marcillac,M. Martínez, A. Ortiz de Solórzano, Y. Ortigoza, C. Pobes,J. Puimedón,T. Redon,T. Rolón, M.L. Sarsa, L. Torres and J.A. Villar. Nuclear and Astroparticle Physics Group (GIFNA) University of Zaragoza (Spain) Spectrométrie Thermique pour l’Astrophysique et la Physique (STAP) Institut d’Astrophysique Spatiale – IAS (Orsay, France)
Goals of ROSEBUD ROSEBUD scientific website: http://www.unizar.es/lfnae/rosebud/ • Testing of particle detector prototypes in a low background environment. • R&D line: characterization of scintillating materials at low temperature. All materials tested have shown scintillation at low temperature: CaWO4, BGO, LiF, Al2O3and SrF2. • Multi-target approach: use of scintillating bolometers of different materials in the same experimental set-up. • Nuclear recoils discrimination against b/g background through light + heat technique for WIMP search. * Sapphire bolometers: 25, 50, 200 and 1000 g Ge optical bolometer Ø 25 mm Ø 40 mm * light + heat technique has shown to be also a powerful tool for nuclear physics
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
The Scintillating Bolometer Thermal model of a simple bolometer n Properties of bolometers Wide choice of different absorber materials. High energy resolution FWHM. Low energy threshold for particle detection. Particle identification capability in hybrid measurements of heat-light or heat-ionization energies. Dielectric and diamagnetic crystal
The Scintillating Bolometer BGO 92 g Scintillating crystal (absorber) Optical bolometer (Ge disk) Cu frame 20 mK Thermal link Thermal link Ge-NTD thermistor Internal reflecting cavity (Cu coated with Ag) Ge-NTD thermistor
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
Sapphire Bolometer (50 g) Calibration 252Cf & 241Am internal source Light pulse amplitude (mV) Nuclear recoils region Heat pulse amplitude (mV) Particle Discrimination Capability Detector response / alphas 59.5 keV (241Am) c / channel Nuclear recoils spectrum / spectrum 59.5 keV (241Am)
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
Experimental set-up in the old LSC facilites The underground laboratory Canfranc Underground Laboratory (LSC) Tobazo Peak Spanish Pyreness 10 m2 1995 - today ROSEBUD 10 m2 Muon flux decreased by a factor ~105 118 m2 2450 m.w.e. 2.5·10-3 m-2s-1
Experimental set-up in the old LSC facilites The scintillating bolometers BGO (Bi4Ge3O12) Mass 46 g 209Bi: ↑A, sensitive to SI and SD interactions 207Bi contamination (clean BGOs available) / spectrometer ↑Z LiF Mass 33 g Monitoring of neutrons through 6Li(n,t) • Sapphire (Al2O3) • Mass 50 g • 27Al: ↓A sensitive to SI and SD interactions • High β/γ background rejection ↓Z & low energy threshold T = 20 mK
Experimental set-up in the old LSC facilites The dilution refrigerator and shielding
Experimental set-up in the old LSC facilites The Faraday Cage and the cryogenic pumping system 15 Faraday cage (2 2 3 m3) Pumping and control systems
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
Light signal amplitude (mV) Heat signal amplitude (mV) Sapphire Light REF (/ : : NR) 210Po 241Am + 57Co / events 59.5 keV 136.5 keV 122 keV events Light output (α) = 1.3 keV / MeV REF(/ α) = 10.3 ± 1.0 (@ 5.3 MeV ) Light output (γ) = 13.5 keV / MeV REF(γ/ NR) = 17.5 ± 1.5 (@ 200 keV )
BGO Light REF (/ : : NR) 252Cf REF(/:) 209Bi + 232Th daughters
Sapphire Thermal REF (206Pb nuclear recoils:/) Relevant for the calibration of the dark matter signal Thermal REF of NR 206Pb recoils at 103.08 ± 0.10 keV from 210Po source Spectrum of the events in the NR band 206Pb recoil Al2O3
BGO Thermal REF (237Np nuclear recoils:/) BGO irradiation with 241Am source 237Np recoiling nuclei at 92.40 ± 0.12 keV from 241Am source
57Co + 241Am 59.5 keV (241Am) Light pulse amplitude (mV) 136.5 keV (57Co) 122.1 keV (57Co) Heat pulse amplitude (mV) Al2O3 BGO = 0.112 0.013 = 0.058 0.006 h = 0.778 0.103 h = 0.464 0.093 0 = 0.110 0.104 0 = 0.478 0.093 Energy partition in Sapphire and BGO scintillating bolometers Al2O3 + h+ 0 = 1
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
Discrimination of NR down to ≈25 keV Discrimination of NR down to ≈10 keV WIMP searches Particle discrimination power Sapphire Kyropoulos grown BGO Czochralski grown BGO 23
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
The BGO scintillating bolometer as -ray spectrometer The BGO allows to note the background level increase and also to identify its origin 222Rn inside the Pb shielding
The BGO scintillating bolometer as -ray spectrometer Heat channel energy resolution
The LiF scintillating bolometer as neutron spectrometer 6Li(n,t) neutron detection efficiencies of LiF bolometers Thermal n 25meV 1keV capture Resonance capture total elastic scattering
6Li(n,a) resonance NR Scintillating bolometers as neutron spectrometers Fast neutron flux inside the shielding Irradiation of a 33 g LiF and a 50 g Al2O3 scintillating bolometers with 252Cf LiF & Al2O3 / events / events events 6Li(n,) Qth = 4.78 MeV NR Previous work presented at TAUP09: J Phys: Conf Series 203 (2010)012139 Hypothesis: fast neutron flux inside the lead shielding We estimated the region of three parameters (F0,a,T) compatible with experimental data
Scintillating bolometers as neutron spectrometers Fast neutron flux inside the shielding Present work: Testing hypothesis about the fast neutron flux inside the shielding Al2O3 heat NR spectra measured MCNP-PoliMi a = −0.9 T = 1.48 MeV Spectra shape in good agreement Comparison of full experimental data with MC calculation is in progress
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
ROSEBUD in the new LSC facilities http://www.lsc-canfranc.es/
ROSEBUD in the new new LSC facilities Hall B 3 3 4.5 m³
Outline • The ROSEBUD Collaboration • Thescintillatingbolometer • Particlediscriminationcapability • Experimental set-up in theold LSC facilities • Mainresults: Light & heat response todifferentparticles WIMP searchprototypes Gamma and neutronspectroscopy • ROSEBUD in the new LSC facilities • EURECA
UNIZAR and IAS integrated in EURECA EURECA project Institut d’Astrophysique Spatiale IAS http://www.eureca.ox.ac.uk/ • Target mass 1 ton. • Semiconductor bolometers builtwiththetechnology of EDELWEISS (LSM). • Scintillating bolometers builtwiththetechnology of CRESST (LNGS) and ROSEBUD (LSC). • To be carriedout at theModaneUndergroundLaboratory (LSM) in France. SeealsoGillesGerbier’stalk! Universidad de Zaragoza
Conclusions • ROSEBUD is a collaborative effort dedicated to the development of scintillating bolometers for nuclear and particle physics experiments, focusing on rare event search experiments. • Scintillating bolometers characterized by ROSEBUD (Al2O3, BGO and LiF) have shown excellent capabilities for particle discrimination and background rejection. • ROSEBUD is currently moving to the Hall B in the new LSC facilities planning to restart measurements in 2012. New materials are being characterized in IAS. • UNIZAR and IAS also participate in EURECA.
UNIZAR and IAS participation in EURECA • Radiopurity measurements of materials (crystals, cryogenic resins, shieldings, detector components, dilution unit pieces) at LSC using ultra-low background germanium detectors. • Development of new scintillating bolometers. • Test of scintillating bolometers at the Canfranc Underground Laboratory (LSC) in order to characterize and optimize scintillators in a low background environment , evaluating these for use as potential dark matter targets in EURECA.