If you look at your photon spectrum for the 1 MeV case, you can see that
the expected peak at 1 MeV is not there. The explanation has nothing to do
with number of histories or installation problems, rather with (un)healthy
programming practices. I had recommended to use double precision when
typing real numbers in user routines and this case shows how important
such a care is. In your source.f you wrote
TKEFLK (NPFLKA) = 1E-3
and then in USRBDX you put the scoring upper limit exactly at 1 MeV. The
inadequate accuracy of the energy value makes a substantial fraction of 1
MeV photons be cut as comparing to the USRBDX value.
If coding
TKEFLK (NPFLKA) = 1.D-03
you no longer lose them.
Still, putting the scoring limit exactly on your particle energy value is
anyway risky, you can instead easily take a safe margin by extending your
scoring range.
Best wishes
Francesco
**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. +41 22 7678962
fax +41 22 7668854
On Fri, 29 Jun 2018, riya dey wrote:
> It is very surprising to note that those two inputs with their corresponding
> source file, gives me different result. But according to you, you are
> getting same result as expected theoretically. But the same inputs while
> running in my pc give different result. How many histories are you using ?
> For the clarification I am attaching both the input, their source files and
> USRBDX on 22 unit result . Kindly have a look into my results.
>
> Or , is there any installation problem so that I am getting wrong results ?
>
>
> If possible, kindly attach the output files for both the energy.
>
>
> -----Original Message-----
> From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it]
> On Behalf Of Francesco Cerutti
> Sent: 29 June 2018 16:07
> To: riya dey <riyadey_at_barc.gov.in>
> Cc: FLUKA discussion <fluka-discuss_at_fluka.org>; riyadey0293_at_gmail.com
> Subject: RE: [fluka-discuss]: TOTAL FLUENCE
>
>
> Riya:
>
> if you run the two inputs you attached with your source.f embedding the
> respective TKEFLK value (0.001 GeV and 0.0001 GeV), you get *in both
> cases* an integral fluence value on unit 22 of 3.4E-7 per cmq per primary:
>
> Tot. resp. (Part/cmq/pr) 3.4233489E-07 +/- 3.171398 % (1 MeV)
>
> Tot. resp. (Part/cmq/pr) 3.3571294E-07 +/- 0.4070479 % (100 keV)
>
> So the problem is not there.
>
> Still, in the 1 MeV case, you are cutting at scoring level the (limited)
> contribution of photons below 100 keV and above your 10 keV transport
> threshold (these come from the interaction with the soil).
>
> In order to avoid to hard-code in the source.f the energy value and be
> forced to recompile it every time, you can set it in the first WHAT of the
> SOURCE card and acquire it by the statement
>
> TKEFLK (NPFLKA) = WHASOU(1)
>
> Cheers
> Francesco
>
> **************************************************
> Francesco Cerutti
> CERN-EN/STI
> CH-1211 Geneva 23
> Switzerland
> tel. +41 22 7678962
> fax +41 22 7668854
>
> On Fri, 29 Jun 2018, riya dey wrote:
>
>> Dear Expert,
>>
>> In reference to the previously attached two input files, if you get
>> same result for both the energy kindly share the output file.
>>
>> -----Original Message-----
>> From: riya dey [mailto:riyadey_at_barc.gov.in]
>> Sent: 29 June 2018 14:25
>> To: 'Francesco Cerutti' <Francesco.Cerutti_at_cern.ch>
>> Cc: 'riyadey0293_at_gmail.com' <riyadey0293_at_gmail.com>
>> Subject: RE: [fluka-discuss]: TOTAL FLUENCE
>>
>> Dear expert,
>>
>> I am sorry to say that I could not get the issue. The two inputs that
>> I have used for 0.1 MeV and 1 MeV is attached here.
>>
>> -----Original Message-----
>> From: Francesco Cerutti [mailto:Francesco.Cerutti_at_cern.ch]
>> Sent: 29 June 2018 14:15
>> To: riya dey <riyadey_at_barc.gov.in>
>> Cc: FLUKA discussion <fluka-discuss_at_fluka.org>; riyadey0293_at_gmail.com
>> Subject: RE: [fluka-discuss]: TOTAL FLUENCE
>>
>>
>> I guess you forgot to adapt the USRBDX energy interval as you
>> increased the photon energy, this way cutting higher energy photons.
>> In fact, when scoring up to the max photon energy, I get fully
>> consistent results (despite the soil effect)
>>
>> Best
>> Francesco
>>
>> **************************************************
>> Francesco Cerutti
>> CERN-EN/STI
>> CH-1211 Geneva 23
>> Switzerland
>> tel. +41 22 7678962
>> fax +41 22 7668854
>>
>> On Fri, 29 Jun 2018, riya dey wrote:
>>
>>> Dear Expert,
>>>
>>> I changed the cloud media from air to vacuum. Still the total fluence
>>> is different for different energy. Actually, with increasing energy
>>> the total fluence in the detector is decreasing which is not expected
>>> if the photons are propagating in vacuum.
>>>
>>> For example, when energy = 0.1 MeV , total cumulative fluence (two
>>> way
>>> scoring) = 3.33E-7 # per cmq per primary , while when energy = 1 MeV,
>>> total fluence (two way scoring) = 5.03 E-8 # per cmq per primary.
>>>
>>> Even with 1E+8 histories, although the statistical error is very
>>> less, still the two values are different. The sample file is attached
> here.
>>>
>>> -----Original Message-----
>>> From: owner-fluka-discuss_at_mi.infn.it
>>> [mailto:owner-fluka-discuss_at_mi.infn.it]
>>> On Behalf Of Francesco Cerutti
>>> Sent: 28 June 2018 23:12
>>> To: riya dey <riyadey_at_barc.gov.in>
>>> Cc: FLUKA discussion <fluka-discuss_at_fluka.org>
>>> Subject: Re: [fluka-discuss]: TOTAL FLUENCE
>>>
>>>
>>> Dear Riya,
>>>
>>> I'd share your expectation if your photons were travelling in vacuum,
>>> but their interactions with your air hemisphere depend on their energy.
>>>
>>> Also, make sure that the statistical error of your fluence values is
>>> reasonably low.
>>>
>>> As a side note, in your source routine, when typing any real number
>>> put it in double precision (e.g., 1.0D0/3.0D0, or - in this specific
>>> case - the available FLUKA parameter ONETHI).
>>>
>>> Kind regards
>>> Francesco
>>>
>>> **************************************************
>>> Francesco Cerutti
>>> CERN-EN/STI
>>> CH-1211 Geneva 23
>>> Switzerland
>>> tel. +41 22 7678962
>>> fax +41 22 7668854
>>>
>>> On Wed, 27 Jun 2018, riya dey wrote:
>>>
>>>>
>>>> Dear FLUKA Experts,
>>>>
>>>>
>>>>
>>>> I was modelling a hemispherical cloud source ( radius = 10 m)
>>>> emitting photons isotropically. Below the cloud, a detector is
>>>> placed at ( 0,0,200
>>>> cm) with radius R= 200 cm. Now, using USRBDX surface crossing
>>>> fluence rate is estimated in the detector. If we change the energy
>>>> emitting from the source , lets say for 0.1 MeV , 0.5 MeV , 1 MeV ,
>>>> then although the fluence distribution with energy is different ,
>>>> the total no of particles crossing the detector surface should be
>>>> nearly
>> same.
>>>> But total fluence from FLUKA results are different for different
> energy.
>>>>
>>>>
>>>>
>>>> What might be the reason for this ?
>>>>
>>>>
>>>>
>>>> The input files for 0.1 MeV is attached here. The outputs (sum.lis)
>>>> for 0.1 MeV and 0.5 MeV are :
>>>>
>>>>
>>>>
>>>> Total fluence per cmq per primary for 0.1 MeV is = 3.59 E-7
>>>> (one-way
>>>> scoring) , for 0.5 MeV is = 4.73 E-8 (one way scoring)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> With regards,
>>>>
>>>> Riya Dey
>>>>
>>>>
>>>>
>>>
>>
>>
>
__________________________________________________________________________
You can manage unsubscription from this mailing list at
https://www.fluka.org/fluka.php?id=acc_info
Received on Sat Jun 30 2018 - 02:33:40 CEST