Hello
sorry for the late answer.
Looking at your plots (and specifically to the one for 64Cu),
and to your provided tab file,
it seems that the legend on the y axis is not correct, it reads MBq
when it should read Bq. (output of Fluka is in Bq)
Then, I do not find back your results when I run your input: maybe it
was for a different thickness or different energy?
One expects indeed to get 64Cu from the 68Zn(p,aplha+n) reaction,
as in the paper that you probably know,
K. Hilgers et al. Applied Radiation and Isotopes 59 (2003) 343.
It is a delicate reaction, sensitive to Coulomb thresholds in the
entrance and exit channels, Fluka is not aimed to get it perfect,
however we get it within a factor 3 with fluka2020
(fluka2011 was performing worse).
In your input, I see a problem with the region WindNb, 300 microns of
niobium in the beam path before the target, where the beam loses more
than 3 MeV (which are a lot starting from 18!).
Also, the overall size
of the beam is larger than the beamline, thus a correct normalization
is difficult due to beam losses.
As for the cards,
the PHYSICS with
sdum=EVAPORAT should have what(1)=3 to activate it at best (4 is
equivalent to 2),
and it is advisable to add a
PHISICS card with Sdum COALESCE and what(1) =1.0,
even though it should not be very important in this specific situation.
Finally, it can be convenient to use interaction length biasing, to
increase the interaction probability and spend less CPU in tracking
stopping protons. I added for instance
LAM-BIAS 0.001 ZnMIX INEPRI
(note that biasing is automatically taken into account by the scoring
routines)
Hope this helps
Paola
> Dear Fluka Experts,
>
> I am trying to simulate proton irradiation of the pure Zn and enriched
> Zn-68 discs in C 18 cyclotron.
> Here are some results that I received.
>
>
> Pure Zinc-68 solid target bombardment
>
> a)
> [cid:image020.jpg_at_01D61D47.71784800]
> b)
> [cid:image021.png_at_01D61D47.71784800]
>
> Figure 41 (a) Relation between proton beam energy and Nb degrader
> thickness and (b) 68Ga (67.71(9) min) yields calculated in FLUKA for range
> of proton beam energies and pure 68Zn target thicknesses.
> [cid:image022.png_at_01D61D47.71784800]
>
> Figure 42 67Ga (3.2612(6) d) yields calculated in FLUKA for 68Zn pure
> targets.
> [cid:image023.png_at_01D61D47.71784800]
> Figure 43 Ratios of the 67Ga to the 68Ga yield vs proton beam energy for
> 68Zn pure targets.
> [cid:image024.png_at_01D61D47.71784800]
> Figure 44 64Cu (12.700(2) h) yields calculated in FLUKA.
>
> [cid:image025.png_at_01D61D47.71784800]
>
> Figure 45 Ratios of the 64Cu yield to the 68Ga yield vs proton beam
> energy.
>
> Zinc-68 enriched solid target bombardment
>
>
> a)
> [cid:image026.jpg_at_01D61D47.71784800]
> b)
> [cid:image027.png_at_01D61D47.71784800]
>
> Figure 50 (a) Relation between proton beam energy and Nb degrader
> thickness and (b) 68Ga (67.71(9) min) yields calculated in FLUKA for range
> of proton beam energies and 68Zn enriched target thicknesses.
> [cid:image028.png_at_01D61D47.71784800]
>
> Figure 51 67Ga (3.2612(6) d) yields calculated in FLUKA for 68Zn enriched
> target.
>
>
> [cid:image029.png_at_01D61D47.71784800]
> Figure 52 Ratios of the 67Ga to the 68Ga yield vs proton beam energy for
> 68Zn enriched targets.
>
> [cid:image031.png_at_01D61D47.71784800]
> It is very strange that for pure Zn and for Zn-68 target I received a lot
> of Cu-64 which is not expected with such low energies that I use.
> Could you please have a look and propose a possible explanation for that?
> I also attach one of my input files and results.
>
> Kind Regards
>
> --
> Adam Dabkowski MSc
>
> Cyclotron Engineer
> Wales Positron Emission Tomography Imaging Centre (PETIC)
>
> Cardiff University School of Medicine
> College of Biomedical and Life Science
> Heath Park
> Cardiff
> CF14 4XN
>
> Tel: +44 02920 745787 / 07511 196842
> Email: dabkowskia_at_cardiff.ac.uk<mailto:dabkowskia_at_cardiff.ac.uk>
> Peiriannydd Cyclotron
> Canolfan Delweddu Tomograffeg Gollwng Positronau Cymru
>
> Ysgol Meddygaeth Prifysgol Caerdydd Coleg y Gwyddorau Biofeddygol a Bywyd
> Parc y Mynydd Bychan
> Caerdydd
> CF14 4XN
>
> Tel: +44 02920 745787 / 07511 196842
> E-bost: dabkowskia_at_caerdydd.ac.uk<mailto:dabkowskia_at_caerdydd.ac.uk>
>
>
>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Mon May 11 2020 - 19:21:27 CEST