Dear Lee,
You can interpret the values you specify (from the summary file created with USYSUW) as follows: for example, the differential yield of 0.1 GeV^-1 you get in the energy interval 0-0.01 GeV simply means that 0.1 GeV^-1*0.01GeV=1E-03 neutrons with E<10 MeV were produced in inelastic hadronic interactions within your entire geometry (also in the surrounding air). Of course this is consistent with the value you got for the larger energy interval, since most neutrons are below 10 MeV.
From the link you included in your file, I guess that you are only interested in neutrons produced in following reaction:
p + O18 -> F18 + n
If this is the case, you should not forget that a non-negligible fraction of neutrons also emerge from other processes, e.g.:
p + O18 -> O17 + n + p
p + O18 -> N14 + n + alpha
USRYIELD will count all neutrons, also those from the latter interactions.
If you are only interested in the first reaction, you could for example use USDRAW in the MGDRAW user routine. By including
'(RESNUC)', you have access to the atomic and mass number of the residual nucleus and you can filter neutrons accordingly. I included some sample code below.
Cheers, Anton
* Check that incoming particle is a proton and that interaction is inelastic:
IF ( JTRACK .EQ. 1 .AND. ICODE .EQ. 101 ) THEN
* Check that residual nucleus is F18:
IF( ICRES .EQ.9 .AND. IBRES .EQ.18 ) THEN
* Loop over all secondaries
DO 99 INMB = 1, NP
* Check that secondary particle is a neutron
IF ( KPART( INMB ) .EQ. 8 ) THEN
* Here you might want to write to a file e.g. the neutron energy TKI (INMB ) or simply count neutrons
ENDIF
99 CONTINUE
ENDIF
ENDIF
________________________________
From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] on behalf of Chenyen Lee [chenyenlee_at_gmail.com]
Sent: 29 November 2013 14:28
To: fluka-discuss_at_fluka.org
Subject: [fluka-discuss]: Interpretation of cross section and yield from USRYIELD
Dear Forum :
I am learning how to score the cross section and yield of 18O(p,n) reaction.
I am confused interpreting the output from USRYIELD.
Part 1. The cross section
The proton beam energy is 0.015GeV( 15MeV).
The XS0-0.01, 61 bin scoring the neutron binning from 0 to 10MeV, the results of cross section gives around 30mb/0.01GeV.
The XS0-1, 65 bin scoring the neutron binning from 0 to 1GeV, the results of cross section gives 0.3mb/1GeV.
What is the cross section of 18O(p,n) at 15MeV, how to interpret it if I want to compare it with the recommended cross section ?
https://www-nds.iaea.org/medical/o8p18f0.html
Part 2. The yield
The Yd0-0.01, 63 bin scoring the neutron yield from 0 to 10MeV gives around 0.1 /0.01GeV.
The Yd0-1, 66 bin scoring the neutron binning from 0 to 1GeV gives 1E-03/1GeV.
How many neutron generated from 18O(p,n) per 15MeV proton.
I know most of the emitting neutron is below 10MeV,but it confuse me how to interpret different binning.
Thanks in advance
Lee
--
03-3281200-3591
0972164977<tel:0972164977>
Chenyen Lee
Department of Nuclear Medicine
Chang Gang Memorial Hospital
Linko,Taiwan
Received on Fri Nov 29 2013 - 20:42:15 CET