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Motivation for new experiment

Motivation for new experiment. Aim: Investigate halflife of alpha emitters in different environments Idea proposed by C. Rolfs Electron screening seen in d-d scattering (metal vs insulator) Proposed effect also in radioactive decay (Debye Model) Experimental indications

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Motivation for new experiment

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  1. Henrik B Jeppesen, INTC meeting 30th of October 2006

  2. Motivation for new experiment • Aim: Investigate halflife of alpha emitters in different environments • Idea proposed by C. Rolfs • Electron screening seen in d-d scattering (metal vs insulator) • Proposed effect also in radioactive decay (Debye Model) • Experimental indications • 22Na (beta+), 7Be (EC) and 210Po (alpha decay) • All measured via activity change at different temperatures B. Limata et al., Eur. Phys. J. A28 (2006) 251 B. Wang et al., Eur. Phys. J. A28 (2006) 375 B. Limata et al., Submitted to Eur. Phys. J. A Henrik B Jeppesen, INTC meeting 30th of October 2006

  3. Alpha-decay test at ISOLDE Test performed at ISOLDE (June 2006) Decay of 221Fr in Au, W, Si and Plastic at room temperature Inconclusive results: < 1 % Need precision of 0.1 % or less Also interesting to test temperature dependence J. Byskov-Nielsen and P. Wright Summer Student Report 2006 Henrik B Jeppesen, INTC meeting 30th of October 2006

  4. Direct halflife measurements • 221Fr (4.9 min) online measurement • Need to repeat measurements • Measured for more than 10 halflives (1-2 hours) • Measurements at room temp and in NICOLE (4 K and 10 mK ) in parallel • 224Ra (3.66 d) offline measurement • One measurement gives sufficient statistics • Collections at HV platform • Metal and non-conductor for room temp. • Metal for NICOLE measurement • Measure alpha particle energies • Ealpha sensitive to screening effects Henrik B Jeppesen, INTC meeting 30th of October 2006

  5. Activity measurement • 226Ra (1600 y) measurement • Collections at HV platform • Metals and non-conductor (Cu, Au, Pd and Si) • Measurements performed in Bochum/Germany • Activity measurements at different temperatures • Room temperature down to 1 K • Measure gamma rays • Less sensitive to deadlayers and thermal effects Henrik B Jeppesen, INTC meeting 30th of October 2006

  6. Yields and collection times • For the direct halflife measurements we need: • Activities of 100-1000 counts/s with solid angle of 1 % • For the activity measurements we need: • Activities of 10 counts/s with solid angle of 1 % Henrik B Jeppesen, INTC meeting 30th of October 2006

  7. Beam Request For the experiment we request: 2 shift for optimization of beam purity 1.5 shifts for sample and temperature changes in NICOLE 1.5 shift for 221Fr beam on Si at 4 K 1.5 shift for 221Fr beam on Au at 4 K 1.5 shift for 221Fr beam on Au at 10 mK 2 shift for 224Ra collection at HV platform 2 shift for 226Ra collection at HV platform In total 12 radioactive shifts and 1 shift for beam tuning Henrik B Jeppesen, INTC meeting 30th of October 2006

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