Re: [fluka-discuss]: neutron production from thin tungsten

From: George Kharashvili <georgek_at_jlab.org>
Date: Mon, 16 Dec 2013 16:53:55 -0500 (EST)

Dear Takashi,

We tried this with FLUKA using the user "source" routine. The example of our approach is the attached routine. It's built using the standard FLUKA example as a template, with modifications that include the routines to generate the spectrum of equivalent photons. The idea is to generate incident electrons as beam particles, and add virtual gammas to the incident flux as real gammas, with the theoretical spectrum according to Budnev et.al. (Please see presentations by George Kharashvili and myself at the last year's FLUKA workshop in Vancouver).
To conserve energy, in the events with virtual gamma, energy of the electron is decreased correspondingly.
In this approach, one can score all hadronic processes in the thin target. It will also be OK to use this approach if there's a thick absorber right after the target - the electromagnetic cascade in it won't be significantly disturbed. Of course this is not a complete solution for the electronuclear production in general case, only in these two applications. Please give it a try if you like - we'd be very interested to see the comparison.

Best regards,
Pavel Degtiarenko

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Dear Takashi and FLUKA users,

Since the above referenced presentation is no longer available through the course website, I'm adding it as an attachment.
I would also like to add that the approach described by Pavel was tested for thin and thick target activation by 2.3 and 3.3 GeV electrons. We have not finished full data analysis yet, but a rough look at the results suggests that using this source routine activation rates increase in thin targets and remain unchanged in thick targets when compared to monoenergetic electrons.

Cheers
 -George

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----- Original Message -----
From: "Takashi Maruyama" <tvm_at_SLAC.Stanford.EDU>
To: "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>
Sent: Monday, December 16, 2013 12:50:54 PM
Subject: [fluka-discuss]: neutron production from thin tungsten

We are setting up an experiment at JLab where 2.2 GeV electron beam is incident on 0.125% r.l. (about 4 microns thick) Tungsten target. As we want to operate FPGA at 17 cm from the target, we are trying to estimate neutron production. In such a thin target, interactions would take place via virtual photon exchange. FLUKA is very reliable in estimating neutron production from thick target (real photon interactions), but is there a way to setup FLUKA to handle virtual photon interaction? Is there any back of the envelop estimation on neutron production from thin target?

  Takashi Maruyama
  SLAC




Received on Tue Dec 17 2013 - 00:56:08 CET

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