1 / 24

O ptical T ime P rojection C hamber for radon and thoron detection

O ptical T ime P rojection C hamber for radon and thoron detection. Wojciech Dominik Zenon Janas Krzysztof Miernik Marek Pf ü tzner. Institute of Experimental Physics Warsaw University. PMT CCD. visible light. 1 m s/cm. Gate. O ptical T ime P rojection C hamber.

dstory
Download Presentation

O ptical T ime P rojection C hamber for radon and thoron detection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Optical Time Projection Chamber for radon and thoron detection Wojciech Dominik Zenon Janas Krzysztof Miernik Marek Pfützner Institute of Experimental Physics Warsaw University

  2. PMT CCD visiblelight 1 ms/cm Gate Optical Time Projection Chamber 1 atm. gas: 49% He 49% Ar 1% N2 1% CH4 M. Ćwiok et al., IEEE TNS, 52 (2005) 2895

  3. OTPC at Warsaw Chamber active volume: 20 x 20 x 15 cm3 Materials used: Stesalit fibreglass PCB plates Pyrex optical window

  4. Registration of a particle CCD PMT

  5. Principle of 3D track reconstruction z a vdt1 vdt2 Lxy Total track length: Inclination angle: vd– electron drift velocity  10 mm/ms

  6. What one can measure with OTPC ? • length and position on XY plane (from camera picture) • length of projection on Z axis (from the length of the PMT signal) • no Z coordinate • energy (from the total track length) • charge of the particle (from the energy loss) • time and position correlation between succesive a-decays • - no sensitivity for electrons

  7. Example: 214Po a-decay CCD Dt= 5 ms PMT Lxy=115 mm

  8. Example: energy loss along the particle track projection of CCD picture fit of Bethe-Bloch formula

  9. T= 0 min T= 3 min a218Po a222Rn Example: correlation between succesive a-decays - tracks originate from the same XY position- track lengths compatible with the 222Rn and 218Po a energies

  10. OTPC background measurement -5hours measurement - circles mark the beginning of the tracks Total of 260 tracks - most of them start from the walls 14 tracks starting from the center Y - position X - position

  11. Tracks starting from the central region (16 x 16 x 15 cm3 gas volume ?) Background activity estimate

  12. 2161 5 ms Search for 220Rn - a -216Po - a decay - two triggers within 300 ms gate 155 ms 216Po 9 cm 220Rn

  13. Range ofa particles in Ar(50%) + He (50%) gas 1 atm 216Po 220Rn

  14. Decays in the center (thoron gate)

  15. Decays from the walls (thoron gate)

  16. Time correlation between two a particles

  17. Background thoron activity estimate

  18. 16x16 mm2 Super-Kamiokande radon detector S = 2(counts/day)/(1 mBq/m3) Background – 2.4± 1.3 counts/day Y. Takeuchi et al.. NIM A 421 (1999) 334

  19. 100 cm 15 cm 50 cm 20 cm 50 cm OTPC for radon detection 20 cm V = 6·10-3 m3 S = 6·10-3 m3 1 mBq/m3  24 h = 0.5 (counts/day) / (1 mBq/m3) V = 0.25 m3 S = 0.25m3 1 mBq/m3  24 h = 21.6 (counts/day) / (1 mBq/m3) Background: 200 mBq/m3 radon 20 mBq/m3 thoron

  20. 220Rn56 s 6.29 212Po300 ns 216Po145 ms 212Bi61 m 6.78 8.78 212Pb10.6 h 208Pbstable 6.1 208Tl3 m 220Rn decay products

  21. 5.49 222Rn3.8 d 210Po138 d 214Po164 ms 218Po3.1 m 214Bi20 m 6.00 7.69 5.30 210Bi5 d 210Pb22.3 y 206Pbstable 5.45 4.65 214Pb27 m 210Tl1.3 m 206Tl4.2 m 222Rn decay products

  22. 819

More Related