Cristina Cozzini (Oxford), IDM 2004, Edinburgh CRESST-II background discrimination: detection of 180...
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Transcript of Cristina Cozzini (Oxford), IDM 2004, Edinburgh CRESST-II background discrimination: detection of 180...
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
CRESST-II background discrimination: detection of 180W natural
decay in a pure alpha spectrum
Paper submitted to Physical Review C
(also available on nucl-ex/0408006)
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
C. Cozzini1, G. Angloher2, C. Bucci3, F. von Feilitzsch4, D. Hauff2, S. Henry1, Th. Jagemann4, J. Jochum, H. Kraus1, B. Majorovits1, V. Mikhailik1, J. Ninkovic2, F. Petricca2, W. Potzel4, F. Proebst2, Y. Ramachers1,*,
W. Rau2, M. Razeti4, W. Seidel2, M. Stark4, L. Stodolsky2, A. J. B. Tolhurst1, W. Westphal4, H. Wulandari4
1. University of Oxford, U.K. 2. MPI für Physik, Munich, Germany3. Laboratori Nazionali del Gran Sasso, Italy4. Technische Universität München, Germany5. Eberhard-Karls-Universität Tübingen, Germany
* Permanent address: University of Warwick, U.K.
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
light reflector
300 g CaWO4 crystal separate cryogenic light detector
thermometer
Superconducting film as thermometer
simultaneous measurement of phonons and scintillation light to discriminate nuclear recoil signals from radioactive background
CRESST PhaseII detector module
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
irradiation with e- and with e- und neutrons
Background Suppression: 98 % 10-20 keV 99.7% 15-25 keV 99.9% > 20 keV
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
1E-3
0.01
0.1
1
10
100
Ni
CrPb
Lu
Yb
ErGd
Eu
Sm
Nd
La Ce
Ba
Y
Sr
ZnCu
Imp
uri
ty c
on
cen
tra
tion
, pp
m
Elements
Russia Ukraine
300 400 500 600 7000
5000
10000
15000
20000
25000
Er3+
Gd3+
Wavelength, nm
600 625 6500
500100015002000
ICP-MS (inductively coupled plasma mass-spectrometry) analysis of the impurities in CaWO4
300 400 500 600 7000
2000
4000
6000
8000
10000
12000
77 K 295 K
Wavelength, nm
X-ray luminescence of CaWO4
RE- impurities in Russian (Y, Nd, Gd and Er all >1 ppm) and Pb (~1 ppm ) in Ukrainian samples
Russian
Ukrainian
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
Half-life for the -decay of 180W obtained independently in four different runs
Counts Exposure Half-life
[kg days] [years]
Run 28 Crystal D 35±4.3 12.268 (1.7±0.2) 1018
Run 27 Crystal D 28.5±5.6 11.745 (1.9±0.4) 1018
Run 23 Crystal E 9 3.467 ≥1.1 1018 (90% C.L.)
Run 22 Crystal B 4 1.140 ≥6.7 1017 (90% C.L.)
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
Half-life for the -decay of 180W obtained from the total exposure (28.62 kg days)
Half life T1/2 = (1.8±0.2) 1018 years
Energy Q = (2516.4±1.1 (stat.)±1.2(sys.)) keV
Previous indication (Danevich et al. Phys. Rev. C 67 (2003))
Half life T1/2 = ( (stat.)±0.3(sys.)) 1018 years8.04.01.1
Cristina Cozzini (Oxford), IDM 2004, Edinburgh
Lower limits (90% C.L) for the half-life times of the non-observed -decay on the other naturally occurring W isotopes (exposure 16.875 kg days)182W T1/2 ≥ 7.7 1021 years
183W T1/2 ≥ 4.1 1021 years
184W T1/2 ≥ 8.9 1021 years
186W T1/2 ≥ 8.2 1021 years