# Re: How to know about the energy of parent particles?

From: Hantao Jing <jinght_at_mail.ihep.ac.cn>
Date: Sun, 18 Sep 2011 22:45:36 +0800

Dear Mr. Battistoni,
Firstly thank you very much for your information. At the same
time, also thank Mary Chin
very much. Based the discussion what Alberto Fasso' wrote, I have
succeeded to obtain the information of parent particles.
the method is: I add the code in USDRAW as
IF(ICODE .EQ. 102) THEN
ISPUSR(1) = JTRACK
ISPUSR(2) = 1

SPAUSR(1) = ETRACK
SPAUSR(2) = AM(JTRACK)
SPAUSR(3) = ETRACK - AM(JTRACK)
END IF.

Then I can count the muon with the parent information in BXDRAW by
IF( JTRACK.EQ.10) THEN
IF(MREG.EQ.3 .AND. NEWREG.EQ.4) THEN

WRITE(60,'(2I7, 4E12.5)') ISPUSR(1),ISPUSR(2),Spausr(1),
& Spausr(2),Spausr(3),ETRACK - AM(JTRACK)
end if
end if

the input file and results in attachments, where the output file have
sort by the pion energy in the fifth column.
I am confused for the output results:
We do find many stopping pion with kinetic energy of zero. but no low pions
with energies from zero to 0.0070103GeV even I have used the PART-THR
card to setting the pion and muon threshold as
PART-THR -1.0E-9 13.0 14.0 1.0 0.0
PART-THR -1.0E-6 10.0 11.0 1.0 0.0 .
I don't know why? the number of primary protons is 10^7 particles.

On the other hand, I want to know: If the pions with energy less to the
threshold of -1.0E-9 decay, these pions are considered
as stopping pions with kinetic energy of zero in FLUKA, is it? If not,
these pions are considered as energy deposition and no
decay happens? How do the FLUKA deal with these pions with energy less
to threshold?

With my best regards,
Hantao Jing

On 2011-9-4 18:47, Giuseppe Battistoni wrote:
> Dear Hantao
> In FLUKA this possibility exists, although it's something that is surely
> an advanced topic. It requires to make use of user routines, and in
> particular
> of mgdraw, struprf, stupre and the common TRACKR, at least.
> It is not soemthing easy to explain by email.
> In any case, as a first step you have to study very carefully
> the section 13.2.13 of fluka2011 manual (mgdraw.f general event interface)
> and 13.2.20 as well: (stupre.f and struprf.f)
>
> Furthermore you can also look in the Discussion what Alberto Fasso' wrote
> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/1606.html
> (notice the mention of LDECAY logical flag!)
>
> The use of these routines allows to record properties of particles' parents.
>
> Best regards
> Giuseppe Battistoni
>
> On 02/09/2011 17:00, Hantao Jing wrote:
>> Dear FLUKA experts,
>> I want to calculated the surface muons from a carbon target.
>> The surface muons decay from rest pions.
>> By examining the energy of pions, I can obtain the surface muon
>> precisely. How to know
>> about the energy of parent pions before it decay?