1. Common analysis of background spectra of proportional counter filled with krypton enriched with 78Kr and natural krypton
Vladimir Kazalov
Baksan Neutrino Observatory
INR RAS
"PARTICLES and COSMOLOGY“, April , 2007, Baksan Valley

2. Ju. Gavriljuk, V. Gavrin, A. Gangapshev,
V. Kazalov, V. Kuzminov, N. Osetrova
Institute for Nuclear Research of the Russian Academy of Sciences, Moscow Russia
S. Panasenko, S. Ratkevich
Karazin Kharkiv National University, Kharkiv, Ukraine
The work is performing in the frames of a Presidium RAS
Fundamental Research Program “Neutrino Physics” and
Supported by RFBR grant №

3. 2ek
+ 2 (2.88 MeV)
Theory:
Experiment:

4. } = 0.481 еа к assumption Se**-----------------> Se*+Se*
Kab= keV, Kab=25.3 keV
Ka1= keV
Ka2= keV
Kb1= keV
Kb2= keV
wk= x-ray
we= e-Auger
Se*
=0.163
} = 0.481
= 0.355 еа к

5. Schematic diagram of 2k-capture event
78Se**  78Se
78Se**  78Se

6. Parameters of the counter
1. Body’s material Cu
2. Total length, mm
1160
3. Fiducial length, mm
595
4. Outer diameter, mm
150
5. Inner diameter, mm
140
6. Central anode material, mm
g.p.tan., 0.010
7. Total volume, l
11.0
8. Fid. Volume, l
9.16
9. Pressure, at
4.51
10. Capacity, pF 31
11. Anode wire resistance , Ohm
613
Æ140
Æ150
Cross-section of the counter
+ - anode

7. Low background shield  1760 mm    15 cm lead
8 cm borated polyethylene
18 cm copper

9. View of installation

10. Electric scheme of the setup
PA1 & PA2 – preamplifiers A1 & A2 – amplifiers
CS – coincidence scheme
DO – digital oscilloscope

11. Real pulse sample

12. Spectrum of 109Cd (88 keV)
Events / keV
Energy, keV

13. Background of 78Kr(T=8400 h)
Events / keV
Energy, keV

14. Background of Krnat (T=3039 h)
Events / keV
Energy, keV

15. Comparison of 78Kr with Krnat
Events / keV
Energy, keV

16. Comparison of 78Kr with Krnat
Events / keV
Energy, keV

17. Three point pulse 17

18. Results:
Events / keV
Energy, keV

19. Number of Kr-78 atoms ,08·1024
Registration efficiency for 3(·)-events ,809
Probability for 3(·)- events - 0,355·0,985
Effectiveness of selection for 3(·)- events - 0,43