ToDo/BachelorArbeit.txt at master · MoritzNeuberger/ToDo · GitHub

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Erste Zusammenfassung:


From a the number of counts in the Kr85 514 keV line together with the expected efficiency from simulations we can derive the specific Kr85 activity of our argon.
    - Specific activity is the activity per quantity of a radionuclide
    - 514 keV line is a unlikely beta decay of the Kr85, energy of the beta particle is (avg: 48keV, max: 173keV) [https://ehs.ucsd.edu/rad/radionuclide/Kr-85.pdf]

In principle we could see the Kr85 beta in the argon before the gamma is registered in the germanium detector.
    - because the signal in the scintillator is earlier than the signal in the germanium detector
The Rb85 state has a lifetime of about 1mus.
    - Rb85 in itself is stable, the excited state takes 1mus to decay a photon is this is the order of magnitude of the time difference between the signals
The 50 keV (mean energy) of this beta might be tricky to see.
    - almost background level
However it is worth looking into this "pre"-coincidence.
    - filter actual Kr85 events

Furthermore, the "decay" of our Ar39/Kr85 continuum will give us a further handle on the Kr85.
    - The beta spectra are to similar (especially taking dead layer effects into account) to disentangle them.
    -> However, the decay will be pretty sensitive to the composition.
      - Kr85 has only 10 yr halflife. Within 2 years of GERDA data the Kr85 should decrease by about 25%.
      - For Ar39 with a halflife of about 270 yr this is not the case.
We see this decay and I am sure we have enough statistics in this part of the spectrum to derive a number.

If we have time we could extend the "pre"-coincidence analysis to search for BiPo's.
This is something we can discuss once we are there.


Inhaltlich

(Tier 4 Daten, Makros schreiben)
- Spektrum auftragen mit Hilfe von Makro vorbereitet in Meeting: um 514keV Peak von 480 ~ 560keV
  - Spektrum von BEGe's bzw. von COAX (Unterschiedliche Genauigkeit der Sensoren betrachten)
  - verschiedene Cuts: (mui und multiplicity) und LAr-Trigger (Effekte von Filtern)
- Punkte um 514keV ohne LAr-Flag heraussuchen und nach Beta aus Zerfall in triggerLAr suchen (40-100keV)
  - Lichtblitz O(1 muis) in Histogram (Events auf Zeit) mit t=0 bei Event in Germanium + Fit
  -> Veto für tatsächlichen Kr90 Zerfall (?)
- Gauß-Fits um 511keV und 514keV Peaks ohne Filter um Unterscheidbarkeit zu zeigen (wird für Monte-Carlo Simulation verwendet (?)) #

Organisation

- GerLA-Interface ausprobieren und überprüfen, ob nützlich
  - Variable setzen (siehe Makro von Christoph), GerLA [+ keylist](findet man in meta)
- "Anmeldung für Bachelorstudenten" mitbringen
- C++ Kurs bei EDX
- gitlab einarbeiten
- root: mehr einarbeiten (z.B. Trees, Histogramme,Fits)