Cryogenic particle detection at the Canfranc Underground Laboratory First International Workshop for the Design of the ANDES Underground Laboratory Centro

Cryogenic Cryogenic particle particle

detection at the detection at the Canfranc Canfranc

Underground Underground LaboratoryLaboratory

First International Workshop for the Design of the ANDES Underground LaboratoryCentro Atómico ConstituyentesBuenos Aires, Argentina11-14 April, 2011

OutlineOutlineOutlineOutline 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





Main results:





EURECA

Institut d’Astrophysique Spatiale IAS (Orsay, France)

Universidad de Zaragoza UNIZAR (Spain)

Canfranc Underground

Laboratory (LSC)

ROSEBUD CollaborationROSEBUD Collaboration(Rare Objects SEarch with Bolometers UndergrounD)(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.

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: CaWO4, BGO, LiF, Al2O3

and SrF2.

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 Goals of ROSEBUD ROSEBUD scientific website: http://www.unizar.es/lfnae/rosebud/

Goals of ROSEBUD Goals of ROSEBUD ROSEBUD scientific website: http://www.unizar.es/lfnae/rosebud/

Sapphire bolometers: 25, 50, 200 and 1000 g

Ø 25 mmØ 40 mm

Ge optical bolometer





Main results:





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7

Thermal model of a simple bolometer

CE

T

3

D

TC

Properties of bolometers1. 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 BolometerThe Scintillating BolometerThe Scintillating BolometerThe 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 BolometerThe Scintillating BolometerThe Scintillating BolometerThe Scintillating Bolometer





Main results:





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Particle Discrimination CapabilityParticle Discrimination CapabilityParticle Discrimination CapabilityParticle Discrimination Capability

Nuclear recoils spectrum

c / channel

59

.5 k

eV

(2

41A

m)

59.5 keV (241Am)/ spectrum

Nuclear recoilsregion

Detector response

alphas/





Main results:





EURECA

Canfranc Underground Laboratory (LSC)

2450 m.w.e.2450 m.w.e.

Tobazo PeakSpanish Pyreness

ROSEBUD

12

Muon flux decreased by a factor ~105

10 m2

10 m2

1995 - today

118 m2

Experimental set-up in the old LSC facilitesExperimental set-up in the old LSC facilitesThe underground laboratoryThe underground laboratory

2.5·10-3 m-2s-1

13

LiFMass 33 gMonitoring of neutrons through 6Li(n,t)

Sapphire (Al2O3)Mass 50 g27Al: ↓A sensitive to SI and SD interactionsHigh β/γ background rejection ↓Z & low energy threshold

BGO (Bi4Ge3O12)Mass 46 g209Bi: ↑A, sensitive to SI and SD interactions207Bi contamination (clean BGOs available)/ spectrometer ↑Z

T = 20 mK

Experimental set-up in the old LSC facilitesExperimental set-up in the old LSC facilitesThe scintillating bolometersThe scintillating bolometers

14Experimental set-up in the old LSC facilitesExperimental set-up in the old LSC facilitesThe dilution refrigerator and shieldingThe dilution refrigerator and shielding

Faraday cage(2 2 3 m3)

Pumping and control systems

15Experimental set-up in the old LSC facilitesExperimental set-up in the old LSC facilitesThe Faraday Cage and the cryogenic pumping systemThe Faraday Cage and the cryogenic pumping system





Main results:





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Sapphire Light REF Sapphire Light REF ((// : : : NR) : NR)

Sapphire Light REF Sapphire Light REF ((// : : : NR) : NR)

59

.5 k

eV

12

2 k

eV

13

6.5

keV

241Am + 57Co

Light output (γ) = 13.5 keV / MeV

REF (γ / NR) = 17.5 ± 1.5 (@ 200 keV )

Light output (α) = 1.3 keV / MeV

REF ( / α) = 10.3 ± 1.0 (@ 5.3 MeV )

/

even

ts

events

210Po

18

BGO Light REF BGO Light REF ((// : : : NR) : NR)

252Cf

REF(/:)

209 Bi + 232 Th daughters

19

Sapphire Thermal REF (Sapphire Thermal REF (206206Pb nuclear recoils:Pb nuclear recoils://))Sapphire Thermal REF (Sapphire Thermal REF (206206Pb nuclear recoils:Pb nuclear recoils://))

206Pb recoils at 103.08 ± 0.10 keV from 210Po source

206Pb recoilSpectrum of the events

in the NR band

Thermal REF of NRRelevant for the calibration of the dark matter signal

syststatrecoilsnuclearREF 056.0008.0008.0044.1)/:(

Al2O3

BGO irradiation with 241Am source

BGO Thermal REF (BGO Thermal REF (237237Np nuclear recoils:Np nuclear recoils://))BGO Thermal REF (BGO Thermal REF (237237Np nuclear recoils:Np nuclear recoils://))

237Np recoiling nuclei at 92.40 ± 0.12 keV from 241Am source

syststatrecoilsnuclearREF 302.0004.0015.0937.0)/:(

21

Energy partition in Sapphire and BGO Energy partition in Sapphire and BGO scintillating bolometersscintillating bolometers

Energy partition in Sapphire and BGO Energy partition in Sapphire and BGO scintillating bolometersscintillating bolometers

Al2O3

+ h + 0 = 1

0 = 0.478 0.093 = 0.058 0.006h = 0.464 0.093

BGO

0 = 0.110 0.104 = 0.112 0.013h = 0.778 0.103

Al2O3





Main results:





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C.L (1 tailed) E (keV)

90 % 8.7

95 % 10.0

99 % 13.0

99.9 % 17.1

99.99 % 21.3

SapphireKyropoulos grown

C.L (1 tailed) E (keV)

90% 23.5

99.9% 33.3

BGOCzochralski grown

BGO

Discrimination of NR down to ≈25 keV

Discrimination of NR down to ≈10 keV

WIMP searchesWIMP searchesParticle discrimination powerParticle discrimination power





Main results:





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25

222Rn inside the Pb shielding

The BGO allows to note the background level increase

and also to identify its origin

The BGO scintillating bolometer as The BGO scintillating bolometer as -ray -ray spectrometerspectrometer



Heat channel energy resolution

1keV25meV

capture

elastic scatterin

g

total

Thermal n

27

Resonance capture

The LiF scintillating bolometer as neutron spectrometerThe LiF scintillating bolometer as neutron spectrometerThe LiF scintillating bolometer as neutron spectrometerThe LiF scintillating bolometer as neutron spectrometer

6Li(n,t) neutron detection efficiencies of

LiF bolometers

NR

Irradiation of a 33 g LiF and a 50 g Al2O3 scintillating bolometers with 252Cf

6Li(n,) resonance

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 (0,,T) compatible with experimental data

LiF & Al2O3

TdE

eTE T

E

)1(0

6Li(n,)

Qth = 4.78 MeV

6Li(n,)

Qth = 4.78 MeV

/

even

ts

/

even

ts

NRNR

/

even

ts

/

even

ts

events events

Scintillating bolometers as neutron spectrometersScintillating bolometers as neutron spectrometersFast neutron flux inside the shieldingFast neutron flux inside the shielding


Present work: Testing hypothesis about the fast neutron flux inside the shielding

Al2O3 heat NR spectrameasured MCNP-PoliMi

Spectra shape in good agreementComparison of full experimental data with MC calculation is in progress

= −0.9 T = 1.48 MeV

TdE

eTE T

E

)1(0







Main results:





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ROSEBUD in the new LSC facilitiesROSEBUD in the new LSC facilitiesROSEBUD in the new LSC facilitiesROSEBUD in the new LSC facilitieshttp://www.lsc-canfranc.es/

ROSEBUD in the new new LSC facilitiesROSEBUD in the new new LSC facilitiesHall BHall B


3 3 4.5 m³







Main results:





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 EURECAUNIZAR and IAS integrated in EURECAUNIZAR and IAS integrated in EURECAUNIZAR and IAS integrated in EURECA

http://www.eureca.ox.ac.uk/

See also Gilles Gerbier’s talk!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 (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.

ConclusionsConclusions

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 EURECAUNIZAR and IAS participation in EURECAUNIZAR and IAS participation in EURECAUNIZAR and IAS participation in EURECA

Documents

Cryogenic particle detection at the Canfranc Underground Laboratory First International Workshop for the Design of the ANDES Underground Laboratory Centro