From: me@marychin.org
Date: Tue Dec 12 2006 - 17:53:05 CET
Alberto,
Definitely more elegant! Didn't know there was such a variable. New to
FLUKA. Thanks a trillion this time!
:)
Alberto Fasso' wrote:
> Thank you, but yesterday, because I was focusing on finding the cause of the
> error, I overlooked a more obvious and elegant way to do what you want.
> Primary particles can be distinguished by their generation number.
> Therefore you could change the test to:
> IF (ICODE.EQ.101 .AND. LTRACK.EQ.1) THEN
> LTRACK is an integer and you can safely test for equality.
>
> Alberto
>
> On Tue, 12 Dec 2006, me@marychin.org wrote:
>
>
>>You are absolutely right. Thanks a million Alberto!
>>
>>Alberto Fasso' wrote:
>>
>>>The reason is probably in your test
>>> ETRACK.EQ.PBEAM
>>>both ETRACK and PBEAM are real (actually double precision) quantities, and
>>>it is well known that comparisons of such quantities should be done only
>>>by .LE. .LT. .GE. or .GT. Equality can be spoiled by rounding errors.
>>>Suppose for instance that PBEAM has been input as 21.5, but ETRACK
>>>for some reason is 24.99999999999999D0. For computing purposes it is the same
>>>thing, but the test of equality would fail. I suggest that you change your test
>>>into:
>>> IF (ICODE.EQ.101 .AND. ETRACK.GE.PBEAM*ONEMNS) THEN
>>>(ONEMNS is predefined in FLUKA as 0.999999999999999D+00)
>>>
>>>Alberto
>>>
>>>
>>>On Mon, 11 Dec 2006, me@marychin.org wrote:
>>>
>>>
>>>
>>>>Dear FLUKA friends,
>>>>
>>>>I started monoenergetic photons in homogeneous lead. Simulations were
>>>>repeated for different incident energy, ranging from 7.5 to 29.5 MeV. My
>>>>USDRAW in mgdraw.f has:
>>>> IF (ICODE.EQ.101 .AND. ETRACK.EQ.PBEAM) THEN
>>>> J = 0
>>>> DO I = 1, Np
>>>> IF (Kpart(I)==8) THEN
>>>> J = J + 1
>>>> END IF
>>>> END DO
>>>> WRITE (IODRAW) J
>>>> END IF
>>>>so that only photons at incident energy undergoing inelastic
>>>>interactions scores. Slowing down photons were not allowed to score. I
>>>>basically mean to count the number of (g,n), (g,2n) and (g,3n) events.
>>>>When the count is plotted against the incident energy, I expect
>>>>the plot to resemble the photoneutron cross section. Generally results
>>>>appear as expected except that at incident energies 21.5, 25.5 and 29.5
>>>>MeV, I miraculously get zero counts. Zero counts were obtained at
>>>>exactly the same three energies when the simulation was repeated with
>>>>carbon and calcium. I can't understand the abrupt zero and the
>>>>discontinuity. Could someone please help. Have I missed something?
>>>>
>>>>My results for lead is as follows. Please note the region of interest I
>>>>have zoomed into between 21 and 22 MeV. 21.4, 21.49 and 21.6 all
>>>>produced non-zero counts while 21.499 and 21.5 produced zero.
>>>>MeV (g,0n) (g,n) (g,2n) (g,3n)
>>>>7.5 709 1747 0 0
>>>>8.5 0 11923 0 0
>>>>9.5 0 37225 0 0
>>>>10.5 0 85953 0 0
>>>>11.5 0 181338 0 0
>>>>12.5 0 266842 0 0
>>>>13.5 1 328983 0 0
>>>>14.5 0 242696 17314 0
>>>>15.5 1 90913 76994 0
>>>>16.5 0 20916 80017 0
>>>>17.5 2 5257 65996 0
>>>>18.5 4 1634 52304 0
>>>>19.5 8 572 35742 0
>>>>20.5 9 235 21941 0
>>>>21 13 188 18131 0
>>>>21.1 10 190 17868 0
>>>>21.2 16 148 17409 0
>>>>21.3 10 169 17280 0
>>>>21.4 10 155 17156 0
>>>>21.49 12 157 17694 0
>>>>21.499 0 0 0 0
>>>>21.5 0 0 0 0
>>>>21.6 12 175 17529 0
>>>>21.7 11 158 17700 0
>>>>21.8 18 162 18257 1
>>>>21.9 13 154 18703 9
>>>>22 18 152 19278 18
>>>>22.5 20 161 22008 210
>>>>23.5 40 168 22886 2608
>>>>24.5 32 118 12426 5929
>>>>25.5 0 0 0 0
>>>>26.5 20 75 2865 9170
>>>>27.5 19 94 1715 10760
>>>>28.5 32 85 951 9397
>>>>29.5 0 0 0 0
>>>>
>>>>Attached inp file, as well as photoneutron cross sections for lead. The
>>>>cross section doesn't seem to explain the trend. Calcium, carbon and
>>>>lead are unlikely to have absolute-zero valleys at exactly the same 3
>>>>energies anyway?
>>>>
>>>>Thanks very much.
>>>>
>>>>mary
>>>>
>>>>
>>>>
>>>
>>>
>
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