Dear Santana
Thanks for your explanation
If value of the scored quantity is x with a relative error of y, then can
you tell me how can we reduce this relative error y in fluka simulation?
What I understand is that this y will decrease when I increase number of
primaries
On Thu, Jun 4, 2015 at 12:54 PM, Santana, Mario <msantana_at_slac.stanford.edu>
wrote:
> The (non-dimensional) relative error (which is what tells if your
> simulation has converged) is invariant to scaling.
>
> - Mario
>
> On Jun 3, 2015, at 11:21 PM, Santana, Mario <msantana_at_slac.stanford.edu>
> wrote:
>
> Luckily for all of us your math is wrong.
>
> The error associated to an estimator, (which in turn is also an
> estimator) does not diverge with the sample size (hopefully), but instead
> it converges (it means it almost freezes around one value) as the sample
> increases. By the way, the speed of convergence (also an estimator) is
> roughly the inverse square root of the sample size.
>
> Have a look here http://en.wikipedia.org/wiki/Moment_%28mathematics%29
>
> I believe that a crash course on statistics and general Monte Carlo
> principles, followed by an introductory FLUKA course will be more efficient
> to help you address your studies.
>
> Mario
>
>
> From: Amit Kumar <amit.live.sal_at_gmail.com>
> Date: Wednesday, June 3, 2015 11:07 PM
> To: HoSeung Song <genesjp_at_skku.edu>
> Cc: Mario Santana <msantana_at_slac.stanford.edu>, fluka-discuss <
> fluka-discuss_at_fluka.org>
> Subject: Re: [fluka-discuss]: Dose calculation (Unit: Gy/min)
>
> Dear HoSeung, Santana
>
> Since there is always some error in the calculated quantities (dose).
> Therefore, if dose has been calculated by simulating 10e5 number of
> primaries(electron in this case) and then if we multiply it with 10e15 to
> get dose corresponding to 10e15 primaries then error will be simply
> multiplied. But if dose has been calculated by simulating 10e15 primaries
> then error will be reduced.
>
> That's why I am thinking 10e15 number of primaries should be used in the
> simulation. I have not seen how much CPS would be appropriate for this
> simulation but I am expecting it to be difficult.
>
> On Thu, Jun 4, 2015 at 10:28 AM, HoSeung Song <genesjp_at_skku.edu> wrote:
>
>>
>>
>> Dear Santana,
>>
>>
>>
>> Thank you for your reply. As I told you, my interest is to simulate
>> dose in Gy/min.
>>
>>
>> The target is now fixed yet. It should be a certain object such as
>> bag, box, and etc. But for now lets say the absorbed dose in air. How can I
>> calculate absorbed in Gy/min.
>>
>>
>> If I simulate a 10E15-16 primary particle number, it seems that
>> simulation time will be so large, is there some way to simulate such kind
>> of large primary numbers?
>>
>>
>> What if I reduce a number of primaries and do the same simulation. can
>> we believe those results?
>>
>>
>> Thank you and sorry for your incovenience.
>>
>>
>> Regards,
>>
>> Ho-seung Song
>>
>>
>>
>>
>>
>> On Wed, Jun 3, 2015 at 10:16 PM, Santana, Mario <
>> msantana_at_slac.stanford.edu> wrote:
>>
>>> Hi HoSeung,
>>>
>>> Results are normalized per primary (in your case per incident
>>> electron).
>>>
>>> Thus, to normalize your results per minute you need to multiply those
>>> by 7.5E12 x 250 * 60:
>>>
>>> Results 7.5E12 e 250 pulse 60 s
>>> ----------- x --------------- x --------------- x -----------
>>> e pulse s min
>>>
>>> Please note that Gy is the unit for absorbed dose density [J/kg], so
>>> you should score it in your target of interest, not in air (unless you want
>>> to know the absorbed dose in air).
>>>
>>>
>>>
>>> From: HoSeung Song < genesjp_at_skku.edu>
>>> Date: Wednesday, June 3, 2015 7:26 AM
>>> To: fluka-discuss < fluka-discuss_at_fluka.org>
>>> Subject: [fluka-discuss]: Dose calculation (Unit: Gy/min)
>>>
>>>
>>>
>>> Dear Fluka users,
>>>
>>>
>>> I am conducting a simulation with 15 MeV electron beam to tunsgen target
>>> to generate photon and neutron. After the target, I put conical shape
>>> collimator to focus the photon. I want to calculate a photon dose (Gy/min)
>>> at the certain distance from the target (example: 1m, 2m, 3m and etc.).
>>>
>>>
>>> 1. For a input card, I used USRBIN (dose-eq), AUXSCORE (photon) to score
>>> the photon equivalent dose, and the unit is pSv/primary. Is this true?
>>>
>>> The specification of the accelerator is as follows;
>>>
>>> - number of electrons per pulse: 7.5*10^12
>>> - pulse frequency: 250Hz
>>> - pulse duration: 6us
>>>
>>> With these parameters, I want to calculate a photon-dose (Gy/min) with
>>> FLUKA. I am a beginner of this program and this field. Can you tell me how
>>> to calculate Gy/min at certain point (or surface) with a little bit detail?
>>>
>>> Thank you in advance.
>>>
>>> Regards,
>>> Ho-seung SONG
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>> --
>> Amit Kumar
>> Scientist
>> Bhaha Atomic Research Centre
>> Mumbai
>>
>> Phone No. : 022-25592841
>> Mobile Number: 9969799819
>> Alt. Email Id. amitkumar_at_barc.gov.in
>>
>>
>
>
> --
> Amit Kumar
> Scientist
> Bhaha Atomic Research Centre
> Mumbai
>
> Phone No. : 022-25592841
> Mobile Number: 9969799819
> Alt. Email Id. amitkumar_at_barc.gov.in
>
>
--
Amit Kumar
Scientist
Bhaha Atomic Research Centre
Mumbai
Phone No. : 022-25592841
Mobile Number: 9969799819
Alt. Email Id. amitkumar_at_barc.gov.in
__________________________________________________________________________
You can manage unsubscription from this mailing list at https://www.fluka.org/fluka.php?id=acc_info
Received on Thu Jun 04 2015 - 11:43:45 CEST