Re: HPGe Detector Efficiency Calculation

From: <>
Date: Thu, 21 Jan 2010 14:22:41 +0100

Hello Raul,

I had a discussion with Alessandro A. Porta about two years ago. He helped
me a great deal.

A link to follow:

For a coaxial p-type HPGe, he obtained less than 10% difference between
experiment and simulation and I managed to do quite as well with my own
case (also a coaxial p-type HPGe) (Your energy range tells me that maybe
you too have such a detector).

Alessandro pointed out two things that helped very much : the various
thicknesses of heavy materials must be very well reproduced (aluminum
shield of the detector, etc.) and also the dead layer.

Then, of course the more the source covers the detector (Allessandro used
a Marinelli beaker type, I used SG500 type), the more the efficiency of
the detector is better.

Different types of source can be described by editing the source.f file
which comes with FLUKA.

So, 15% to 25% difference may be quite good results, but they could be
improved if there is some higher accurancy you could put into (source,
thicknesses, etc.).

Hope it helps,



> Dear FLUKA experts,
> I am calculating full energy peak-efficiency of a (broad energy) HPGe
> detector. The simulations were carried out using the nominal values for
> the dimensions of the detector provided by the manufacturer. No
> optimization of these was carried out so far. The calculations were also
> carried out with MCNPX and PENELOPE, and a good agreement was found
> between the three codes.
> The differences found between the experimental and the simulation
> results vary between 15% and 25% (the simulated efficiencies are higher
> than the experimental ones) in the energy range of 50-1500 keV.
> Do you think this is acceptable? If not, do you have any suggestion to
> explain the discrepancies?
> Thank you very much in advance for any help you can provide.
> Best regards,
> Raul Luis
> ITN, Portugal
Received on Thu Jan 21 2010 - 15:33:09 CET

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