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Present and future limitations of SHE in-beam experiments R-D Herzberg.

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Presentation on theme: "Present and future limitations of SHE in-beam experiments R-D Herzberg."— Presentation transcript:

1 Present and future limitations of SHE in-beam experiments R-D Herzberg

2 Outline Decay studies Equipment Present bottlenecks – Separator – Spectrometer – DAQ Sample calculatons In-beam studies Equipment Present bottlenecks – Target – Spectrometer – Recoil ID – DAQ Sample calculations – 253 No, 256 Rf, 260 Sg

3 Decay Studies (high beam: 10 pµA) Target: (Sigurd) – Temperature! Separator: (Sigurd) – Cleanliness – Transmission – Recoil Identification Instrumentation

4 Equipment GREAT – type spectrometer Sensitivity to all emitted radiation Clean Recoil ID DAQ: Triggerless to avoid correlation losses due to deadtime

5 Bottlenecks Geometric efficiencies – Active tape (moving Si) – Can yield extra 25 % over tunnel designs – Very clean – Might induce losses for short primary times. Preamplifiers with large dynamic range required (Recoil -> Alpha -> CE)

6 Bottlenecks II Ge detectors: – Close geometry – Sensitivity to X-rays Conversion electrons – Low thresholds on all Si – Thick Si required

7 DAQ Must be able to handle a large number of channels Common deadtime approaches not really suitable -> triggerless DAQ! Short decays (µs) require digital cards to allow distinction

8 Sample calculation 261 Bh 209 Bi( 54 Cr,2n) 261 Bh XS ~ 0.1 nb (NPA273 (76) 505) To do spectroscopy of 257 Db one needs to see >1000 alpha decays Separator efficiency 60% Br(alpha) = 100% 21 days at 1000 pnA -> straightforward If XS 10 pb and beam 5000 pnA 42 days (marginal)

9 Conclusions No insurmountable problems at the focal plane. Spectroscopy after alpha decay is an excellent way to identify single particle structure in SHE Possible down to 10 pb

10 In-beam Studies Experience with gamma and CE studies Unique set of problems Main challenge is Fission

11 Equipment Target (Wheel) Prompt Spectrometer capable of high rate Separator with large transmission Excellent Recoil ID DAQ capable of high rate

12 Gamma Ray spectrometer Dominant channel is constant ~0.1 - 1b Fission. This limits Ge rate! Target wheel spokes need beam sweeping High granularity and large distance to keep individual rates low (Jurogam, Euroball) Background from entrance windows etc. – Need windowless system!

13 Electron Spectrometer Fission does not readily procuce CE SHE produce more CE than Gamma Delta electrons require HV barrier Generally difficult Rate concentrated near field axis Baseline dirty -> need digital cards

14 SACRED At present, electron experiments Use 20% of the beam current of Gamma experiments. Rate adjustable with HV barrier. Targets need to be thinner (0.25 mg/cm 2 )

15 Recoil ID Mainly the task of the separator Scattered beam Fm recoils

16 Rate calculation basics 10 pnA on 500 µg/cm 2 at 1 µb = 325 Reactions /h At maximum XS ~20 ħ in the system Fission rates adjusted to match experimentally observed Ge rates, then scaled Two spectrometers: 5% and 10% Efficiency e.g. Jurogam or Euroball

17 Bottlenecks Ge rate. Present: 10 kHz/detector With digital electronics and high throughput preamplifiers: 30 kHz/detector, eventual aim is 100 kHz/detector DAQ must handle these rates to preprocess and write to tape. Data rates up to 50MB/s – BGO suppression – Recoil coincidence

18 Sample calculations

19 Conclusions Decay studies will be possible without large changes to existing detector technology and electronics. Target/Separator are crucial. In-beam studies will need highest rate capabilities – electronics, DAQ. Target must allow the beam, 1 nb level possible.

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