Slides - Indico

Building a High Sensi6vity Radon Detector Speaker: Nellie Marangou Conducted at: University College London January 2015 – April 2015 Supervisor: Prof. Ruben Saakyan Group members: Jubair Ahmed, Chris Davenport, Habeel Khalid, Gleb Lukicov, Nellie Marangou, Aditya Mukherjee, Harrison Pim, Michael Schroder, Laurence Sgroi Nellie Marangou 1 Introduc6on Aim To built an electrostaKc radon detector which combines good sensiKvity with a modest cost Background Radon-‐222 is a naturally occurring gas, which appears as the result of decay from Uranium and Thorium. High sensiKvity detecKon of radon is required for experiments like NEMO and LUX. Nellie Marangou 2 Instrumenta6on à  PosiKvely charged α-‐
parKcles were directed away from a negaKvely charged steel cage. à  A collision between a-‐
parKcle and the PIN diode produced a noise signal, which was flaWened by the circuit box preceding the oscilloscope. à  The oscilloscope saved waveforms which exceeded a specific trigger voltage and then passed them on to a computer for further noise filtering and analysis. Nellie Marangou 3 Programming Data acquisiKon and noise filtering were done in Java, while extended analysis and plots were produced in Python. Both used Amazon’s EC2 to overcome processing limitaKons. Dis;nc;on between Decay Event and Noise Event Different Fits to a Decay Event Nellie Marangou 4 Results & Discussion Source in Air Isotope'
Polonium(210,
Polonium(214,
Polonium(218,
!
Count'Rate'/'Bq'
0.016,±,0.002,
0.024,±,0.002,
0.0165,±,0.0009,
Background in Air Isotope'
Count'Rate'/'Bq'
Polonium(210, 0.016,±,0.002,
!
Nellie Marangou 5 Source in Helium Isotope'
Polonium(210,
Polonium(214,
Polonium(218,
Count'Rate'/'Bq'
0.5,±,0.3,
1.23,±,0.04,
0.64,±,0.03,
!
Brief Discussion: The Po-‐214 count rate in helium with the source, (1.23 ± 0.04)Bq, was greater than the count rate in air with the source, (0.024 ± 0.002)Bq, by over 50 Kmes. Possible reasons: à Humidity Effect on PIN diode (corrosion) à Humidity Effect on Alpha Par;cles à Nitrogen and Oxygen in Air Nellie Marangou 6 Conclusion EsKmate of developed detector sensiKvity: Experimental Improvements and Future Plans -‐  ApplicaKon of negaKve HV to the PIN diode -‐  Adding a Carbon Trap -‐  Investment in a new, clean PIN diode Any Ques6ons? Nellie Marangou 7

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