Cryogenic particle detection at the Canfranc Underground Laboratory First International Workshop for the Design of the ANDES Underground Laboratory Centro Atómico Constituyentes Buenos Aires, Argentina April, 2011

OutlineOutline 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

OutlineOutline 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

Institut d’Astrophysique Spatiale IAS (Orsay, France) Universidad de Zaragoza UNIZAR (Spain) Canfranc Underground Laboratory (LSC) 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. Spectrométrie Thermique pour l’Astrophysique et la Physique (STAP) Institut d’Astrophysique Spatiale – IAS (Orsay, France) Nuclear and Astroparticle Physics Group (GIFNA) University of Zaragoza (Spain)

* light + heat technique has shown to be also a powerful tool for nuclear physics 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: CaWO 4, BGO, LiF, Al 2 O 3 and SrF 2. Multi-target approach: use of scintillating bolometers of different materials in the same experimental set-up. Nuclear recoils discrimination against  /  background through light + heat technique for WIMP search. * Goals of ROSEBUD ROSEBUD scientific website: Goals of ROSEBUD ROSEBUD scientific website: Sapphire bolometers: 25, 50, 200 and 1000 g Ø 25 mm Ø 40 mm Ge optical bolometer

OutlineOutline 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

7 Thermal model of a simple bolometer Properties of bolometers 1.Wide choice of different absorber materials. 2.High energy resolution FWHM. 3.Low energy threshold for particle detection. 4.Particle identification capability in hybrid measurements of heat-light or heat-ionization energies. Dielectric and diamagnetic crystal The Scintillating Bolometer n

8 20 mK Internal reflecting cavity (Cu coated with Ag) Ge-NTD thermistor Optical bolometer (Ge disk) Scintillating crystal (absorber) Cu frame Thermal link BGO 92 g Thermal link Ge-NTD thermistor The Scintillating Bolometer

OutlineOutline 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

10 Particle Discrimination Capability Nuclear recoils spectrum c / channel 59.5 keV ( 241 Am)  /  spectrum Light pulse amplitude (mV) Heat pulse amplitude (mV) Sapphire Bolometer (50 g) Calibration 252 Cf & 241 Am internal source Nuclear recoils region Detector response alphas //

OutlineOutline 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

Canfranc Underground Laboratory (LSC) 2450 m.w.e. Tobazo Peak Spanish Pyreness ROSEBUD 12 Muon flux decreased by a factor ~ m today 118 m 2 Experimental set-up in the old LSC facilites The underground laboratory 2.5·10 -3 m -2 s -1

13 LiF Mass 33 g Monitoring of neutrons through 6 Li(n,t)  Sapphire (Al 2 O 3 ) Mass 50 g 27 Al: ↓A  sensitive to  SI and  SD interactions High β/γ background rejection ↓Z & low energy threshold BGO (Bi 4 Ge 3 O 12 ) Mass 46 g 209 Bi: ↑A,  sensitive to  SI and  SD interactions 207 Bi contamination (clean BGOs available)  /  spectrometer ↑Z T = 20 mK Experimental set-up in the old LSC facilites The scintillating bolometers

14 Experimental set-up in the old LSC facilites The dilution refrigerator and shielding

Faraday cage (2  2  3 m 3 ) Pumping and control systems 15 Experimental set-up in the old LSC facilites The Faraday Cage and the cryogenic pumping system

OutlineOutline 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

17 Sapphire Light REF (  /  :  : NR) 59.5 keV 122 keV keV 241 Am + 57 Co Heat signal amplitude (mV) Light signal amplitude (mV) Light output (γ) = 13.5 keV / MeV REF (γ / NR) = 17.5 ± keV ) Light output (α) = 1.3 keV / MeV REF (  / α) = 10.3 ± MeV )  /  events  events 210 Po

18 BGO Light REF (  /  :  : NR) 252 Cf REF(  /  :  ) 209 Bi Th daughters

19 Sapphire Thermal REF ( 206 Pb nuclear recoils:  /  ) 206 Pb recoils at ± 0.10 keV from 210 Po  source 206 Pb recoil Spectrum of the events in the NR band Thermal REF of NR Relevant for the calibration of the dark matter signal Al 2 O 3

BGO irradiation with 241 Am  source BGO Thermal REF ( 237 Np nuclear recoils:  /  ) 237 Np recoiling nuclei at ± 0.12 keV from 241 Am  source

21 Energy partition in Sapphire and BGO scintillating bolometers Heat pulse amplitude (mV) Light pulse amplitude (mV) 57 Co Am 59.5 keV ( 241 Am) keV ( 57 Co) keV ( 57 Co) Al 2 O 3  +  h +  0 = 1  0 =   =   h =  BGO  0 =   =   h =  Al 2 O 3

OutlineOutline 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

23 C.L (1 tailed) E (keV) 90 % % % % %21.3 Sapphire Kyropoulos grown C.L (1 tailed)E (keV) 90% %33.3 BGO Czochralski grown BGO Discrimination of NR down to ≈25 keV Discrimination of NR down to ≈10 keV WIMP searches Particle discrimination power

OutlineOutline 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

Rn inside the Pb shielding The BGO allows to note the background level increase and also to identify its origin The BGO scintillating bolometer as  -ray spectrometer

Heat channel energy resolution

1keV25meV capture elastic scattering total Thermal n 27 Resonance capture The LiF scintillating bolometer as neutron spectrometer 6 Li(n,t)  neutron detection efficiencies of LiF bolometers

NR Irradiation of a 33 g LiF and a 50 g Al 2 O 3 scintillating bolometers with 252 Cf 6 Li(n,  ) resonance Previous work presented at TAUP09: J Phys: Conf Series 203 (2010) Hypothesis: fast neutron flux inside the lead shielding We estimated the region of three parameters (  0, ,T) compatible with experimental data LiF & Al 2 O 3 6 Li(n,  ) Q th = 4.78 MeV  /  events NR  /  events  events Scintillating bolometers as neutron spectrometers Fast neutron flux inside the shielding Scintillating bolometers as neutron spectrometers Fast neutron flux inside the shielding

Present work: Testing hypothesis about the fast neutron flux inside the shielding Al 2 O 3 heat NR spectra measured MCNP-PoliMi Spectra shape in good agreement Comparison of full experimental data with MC calculation is in progress  = −0.9 T = 1.48 MeV Scintillating bolometers as neutron spectrometers Fast neutron flux inside the shielding Scintillating bolometers as neutron spectrometers Fast neutron flux inside the shielding

OutlineOutline 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

31 ROSEBUD in the new LSC facilities

ROSEBUD in the new new LSC facilities Hall B ROSEBUD in the new new LSC facilities Hall B 3  3  4.5 m³

ROSEBUD in the new new LSC facilities Hall B ROSEBUD in the new new LSC facilities Hall B

OutlineOutline 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

EURECA project Universidad de Zaragoza Institut d’Astrophysique Spatiale IAS Target mass 1 ton. Semiconductor bolometers built with the technology of EDELWEISS (LSM). Scintillating bolometers built with the technology of CRESST (LNGS) and ROSEBUD (LSC). To be carried out at the Modane Underground Laboratory (LSM) in France. 35 UNIZAR and IAS integrated in EURECA See also Gilles Gerbier’s talk!

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 (Al 2 O 3, 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 New materials are being characterized in IAS. UNIZAR and IAS also participate in EURECA. Conclusions

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. UNIZAR and IAS participation in EURECA