Re: a cross-check (He 5MeV into gas chamber)

From: Ercan Pilicer (
Date: Wed Jan 17 2007 - 10:27:55 CET

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    Dear Alberto and Sebastien,

    thank you for your comments. below are the some answers and questions as well;

    1. i was mistaken with using WHAT(1)>0.0 for BEAM properties. the true
    way i should use is WHAT(1)<0.0 as kinetic energy for Helium. nothing
    was clear for this in the example.
    2. about Xmin,Ymin,Zmin and Xmax,Ymax,Zmax parameters of URSBIN, it
    makes no problem since FLUKA swaps these parameters accordingly. lucky
    3. i noticed the file size of fort.76 is big and there must be sth
    inside. however could you tell us the use of pawlevbin briefly and
    4. my attention has been drawn to use DELTARAY and EMFCUT options.
    thats ok however where can i find reasonable values for them if that
    is important?
    5. i dont know if these tracks SRIM sees are by DELTARAYs. but it says
    ION RANGE is 46mm when the deposited energy tracks with FLUKAGUI is
    around 2.5cm.
    6. i have been controlling the values for etrack and am(jtrack) by
    dumping into a file. i have noticed it dumps real values for particle
    mass, then i changed energy into a real one.
    7. for ytup(3), i think it makes the same by using either with sngl or
    without. i should better check them again. should i use sngl(XXX) for
    all parameters, and fill HBOOK by converting them into real?
    8. but what happens when i convert a 0.0001 number into integer? it
    becomes 0 for all values less than 0.999.
    9. the most important part i am involved that if there is a way to
    calculate beam particle's range and LET inside a material without
    using any user routines. if there is could you please guide me? i have
    seen some examples for LET with USRYIELD option but i didnt succeed to
    find a value in the unit of MeV/(mg/cm2)

    kindly wishes,

    > Hello Ercan,
    > There is some energy deposited is reg5 (gas) if you put -5.0E-3 instead
    > of 5.0E-3 in WHAT(1) of BEAM card. I check it with the results of SCORE
    > card (4.68512050E-03 GeV/cm³/primary for region 5 scoring code 211.),
    > and the integral calculated by pawlevbin for the binning in logical
    > output 76 is not zero.
    > Your defintions of USRBIN are strange too. You put Xmin, Ymin and Zmin
    > of your binnings in the locations of Xmax, Zmax, Zmax and vice versa.
    > Hope it helps.
    > Regards.
    > Sebastien.
    > Dear Ercan,
    > I see that Sebastien Wurth has already given you some useful answer.
    > I tried to check your input too, but as I said yesterday to another user
    > it is very difficult to do this kind of check when user routines are
    > involved. And you are using 5 of them, plus other routines of your own!
    > Anyway I let you know what I have found out.
    > First, you have chosen no DEFAULTS, which means you are using the
    > NEW-DEFA set of defaults. You have not put any DELTARAY or EMFCUT command
    > in your input, which means that the NEW-DEFA defaults are unchanged.
    > Now, the NEW-DEFA default for delta ray production is 1 MeV, while your beam of
    > alpha particles has 5 MeV momentum = 3.35 keV kinetic energy! Of
    > course you will get nothing with such a low energy. But even if you meant
    > 5 MeV kinetic energy (input it with a minus sign, as suggested by Sebastien),
    > you will not get many delta rays with more than 1 MeV.
    > I guess these delta rays are the tracks that SRIM sees.
    > Also, be careful in setting a proper energy cutoff for electrons,
    > both for transport (EMFCUT) and for production (EMFCUT with SDUM = PROD-CUT).
    > Second, I had a quick look at some of your user routines.
    > You are using systematically real*4 variables, which carries some risk
    > because you are easily going to lose precision in some cases. I understand
    > that it is probably necessary in order to use HBOOK, but why are you not
    > doing all your stuff in double precision, consistently with FLUKA, and
    > convert it to single precision at the last minute just before calling HBOOK?
    > In a similar way, in mgdraw variables are converted to single precision,
    > but only just BEFORE WRITING, in order to reduce the size of the collision file.
    > There are other questionable things:
    > eisci=sngl(etrack)-am(jtrack)
    > why not
    > eisci=sngl(etrack)-sngl(am(jtrack))?
    > And why later on you have dropped the sngl:
    > ytup(3) = etrack-am(jtrack)?
    > Worse:
    > if(sngl(ztrack(1)).eq.real(0.0001))
    > Never use .eq. with a real number! What will happen if sngl(ztrack(1))
    > is = 0.00009999999 or 0.00010000001?
    > In your routine all tests are done with real numbers. Either convert them
    > to integer tests (using NINT for instance), or use .le. or .ge.
    > Kind regards,
    > Alberto
    Ercan Pilicer
    High Energy Physics Department
    Uludag University, Turkey

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