[mcstas-users] TOFRes_sample
Ryoichi Kajimoto
ryoichi.kajimoto at j-parc.jp
Wed Oct 25 08:04:03 CEST 2023
Dear Kim,
To my understanding, the meaning of the code is like the attached figure. Is my understanding correct?
If this is correct, l_full becomes large when thickness is large, while scat_factor = 2*(radius-thickness) becomes small. Then l_full/scat_factor becomes extremely large.
With regard to this, I found that when thickness = 0, which is default, or thickness = radius, the code does not generate an output data. (I tested this with McStas 2.7.2)
I guess that:
- When thickness = 0, t1 = t0 and t3 = t2. This results in l_full = p = 0.
(Function cylinder_intersect(&t1, &t2, x, y, z, vx, vy, vz, radius-thickness, yheight) in line 167 is executed even when thickness = 0.)
- When thickness = radius, scat_factor becomes zero, and p becomes infinity (divided by zero).
Best regards,
Ryoichi
Kim Lefmann wrote on 2023/10/24 18:58:
> Dear Ryoichi,
>
> You are right that in this case scat_factor becomes small - but so does l_full since materials thickness is small. So the fraction is in any case of the order 1.
>
> Of course if you were interested in absolute intensities, the cross section should be weighted differently, as we do in the more realistic samples.
>
> best, Kim
>
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> *From:* Ryoichi Kajimoto <ryoichi.kajimoto at j-parc.jp>
> *Sent:* Tuesday, October 24, 2023 11:14:59 AM
> *To:* Kim Lefmann; pkwi at dtu.dk
> *Cc:* mcstas-users at mcstas.org
> *Subject:* Re: [mcstas-users] TOFRes_sample
> [You don't often get email from ryoichi.kajimoto at j-parc.jp. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification <https://aka.ms/LearnAboutSenderIdentification> ]
>
> Dear Kim,
>
> Thank you for explaining the detail.
> Maybe I understand.
>
> My question is that if scat_factor = 2*(radius-thickness), it becomes very small when thickness is nearly equal to radius. Then l_full/scat_factor becomes extremely large, which seems to be unreasonable.
> Anyhow it may not be a problem because the absolute intensity is not important in resolution calculation.
>
> Best regards,
>
> Ryoichi
>
>
> Kim Lefmann wrote on 2023/10/24 17:34:
>> Dear Ryoichi,
>>
>> Since I wrote the code, please let me explain the logic.
>>
>> For a resolution calculation, the absolute intensity is irrelevant, since you only want to know the widths.
>>
>> The weighing using the fraction l_full/scat_factor is done to correct for the fact that the outer parts of the sample scatter differently from the center part due to different path lengths:
>>
>> l_full is exactly the path length in the sample of this neutron ray
>> scat_factor is the path length for a ray that hits the sample center (and is constant for the full simulation).
>>
>> The latter path length is used as normalization (and to ensure that the units are correct).
>>
>> best, Kim
>>
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>> *From:* mcstas-users <mcstas-users-bounces at mcstas.org> on behalf of Ryoichi Kajimoto <ryoichi.kajimoto at j-parc.jp>
>> *Sent:* Tuesday, October 24, 2023 9:40:56 AM
>> *To:* pkwi at dtu.dk
>> *Cc:* mcstas-users at mcstas.org
>> *Subject:* Re: [mcstas-users] TOFRes_sample
>>
>> [You don't often get email from ryoichi.kajimoto at j-parc.jp. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification <https://aka.ms/LearnAboutSenderIdentification> <https://aka.ms/LearnAboutSenderIdentification <https://aka.ms/LearnAboutSenderIdentification>> ]
>>
>> Dear Peter,
>>
>>> Wrt. the scat_factor, since thickness is an optional parameter (default=0, parametrises an optional "inner hollow”) I believe the formula is OK.
>> Thanks, but there is a line in line 176:
>> p *= l_full/scat_factor; /* Scattering probability */
>> where l_full is "Length of full path through sample."
>>
>> It seems to me that p is defined as the ratio of length of full path through sample to total size of sample. However, if scat_factor is as it is, p can be larger than unity.
>>
>> Best regards,
>>
>> Ryoichi
>>
>>
>> Peter Kjær Willendrup wrote on 2023/10/24 16:12:
>>> Dear Ryochi,
>>>
>>> Once I have the edits in place and a running instrument I will send the modified component to this mailinglist thread.
>>>
>>> Wrt. the scat_factor, since thickness is an optional parameter (default=0, parametrises an optional "inner hollow”) I believe the formula is OK.
>>>
>>> Best
>>> Peter
>>>
>>> On 24 Oct 2023, at 07.20, Ryoichi Kajimoto <ryoichi.kajimoto at j-parc.jp> wrote:
>>>
>>> Dear Peter,
>>>
>>> Thank you for the prompt response. I hope this issue will be solved soon.
>>>
>>> I have another question regarding TOFRes_sample.
>>>
>>> On line 169 of TOFRes_sample.comp, there is a code:
>>> scat_factor = 2*(radius-thickness);
>>>
>>> But is this correct? I think scat_factor should be 2*radius.
>>>
>>>
>>> Best regards,
>>>
>>> Ryoichi
>>>
>>> Peter Kjær Willendrup wrote on 2023/10/24 3:07:
>>> Dear Ryoichi Kajimoto,
>>>
>>>
>>> Thank you for reporting this issue, you are completely right in pointing out that needed modifications are missing in the McStas 3.4 version of TOFRes_sample.
>>> (This has gone unnoticed since a test-instrument for the said component was not defined in our test suite, sorry for this.)
>>>
>>> I have defined a GitHub issue at https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FMcStasMcXtrace%2FMcCode%2Fissues%2F1512&data=05%7C01%7Clefmann%40nbi.ku.dk%7Cde77aece11cf4918c23008dbd471b476%7Ca3927f91cda14696af898c9f1ceffa91%7C0%7C0%7C638337357056579252%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=94nRHavpkrZdgXTsClxXqFXDpVH5DuAZ1gf9tER8tpM%3D&reserved=0 <https://github.com/McStasMcXtrace/McCode/issues/1512> <https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FMcStasMcXtrace%2FMcCode%2Fissues%2F1512&data=05%7C01%7Clefmann%40nbi.ku.dk%7Cde77aece11cf4918c23008dbd471b476%7Ca3927f91cda14696af898c9f1ceffa91%7C0%7C0%7C638337357056579252%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=94nRHavpkrZdgXTsClxXqFXDpVH5DuAZ1gf9tER8tpM%3D&reserved=0 <https://github.com/McStasMcXtrace/McCode/issues/1512>> and will implement the needed
> changes as soon as time allows.
>>>
>>>
>>> Best,
>>> Peter Willendrup
>>>
>>> On 23 Oct 2023, at 13.29, Ryoichi Kajimoto <ryoichi.kajimoto at j-parc.jp> wrote:
>>>
>>> Hi,
>>>
>>> I'm simulating a resolution function of a direct-geometry TOF spectrometer. I use TOFRes_sample() for the sample and Res_monitor() for the monitor.
>>>
>>> My code worked with McStas 3.1, but it cannot be compiled with McStas 3.4.
>>> I would appreciate if you could provide any solution.
>>>
>>> Converting the .instr file to .c with mcstas command worked fine without an error, but compiling it with gcc -O3 -lm stops with an error message attached below.
>>>
>>> I found that Res_monitor.comp and Res_sample.comp were greatly updated in McStas 3.4 but TOFRes_sample.comp was unchanged. I suspect that TOFRes_sample.comp is not compatible with Res_monitor.comp...
>>>
>>> Thank you in advance,
>>>
>>> Ryoichi Kajimoto
>>>
>>>
>>> ==================================
>>>
>>> SIKIResSim.c: In function ‘Table_Read_Handle’:
>>> SIKIResSim.c:7518:60: warning: format ‘%i’ expects argument of type ‘int’, but argument 5 has type ‘long int’ [-Wformat=]
>>> 7518 | fprintf(stderr,"Warning: Read_Table :%s %s Data has %i invalid lines (*****). Ignored.\n",
>>> | ~^
>>> | |
>>> | int
>>> | %li
>>> ......
>>> 7521 | count_invalid);
>>> | ~~~~~~~~~~~~~
>>> | |
>>> | long int
>>> SIKIResSim.c: In function ‘_resmonitor_setpos’:
>>> SIKIResSim.c:13221:6: error: ‘RSsample’ undeclared (first use in this function)
>>> 13221 | if(RSsample && strlen(RSsample))
>>> | ^~~~~~~~
>>> SIKIResSim.c:13221:6: note: each undeclared identifier is reported only once for each function it appears in
>>> SIKIResSim.c: In function ‘class_Res_monitor_init’:
>>> SIKIResSim.c:663:33: warning: format not a string literal and no format arguments [-Wformat-security]
>>> 663 | #define NAME_CURRENT_COMP (_comp->_name)
>>> | ~~~~~~^~~~~~~~
>>> SIKIResSim.c:13781:48: note: in expansion of macro ‘NAME_CURRENT_COMP’
>>> 13781 | if (!strcmp(filename,"\0")) sprintf(filename,NAME_CURRENT_COMP);
>>> | ^~~~~~~~~~~~~~~~~
>>> SIKIResSim.c:641:10: error: ‘_class_Res_sample_parameters’ undeclared (first use in this function); did you mean ‘_class_TOFRes_sample_parameters’?
>>> 641 | &( ((_class_ ## type ##_parameters *) _getvar_parameters(compname))->par )
>>> | ^~~~~~~
>>> SIKIResSim.c:13835:18: note: in expansion of macro ‘COMP_GETPAR3’
>>> 13835 | int *index_ptr=COMP_GETPAR3(Res_sample, res_sample_comp, compindex);
>>> | ^~~~~~~~~~~~
>>> SIKIResSim.c:641:41: error: expected expression before ‘)’ token
>>> 641 | &( ((_class_ ## type ##_parameters *) _getvar_parameters(compname))->par )
>>> | ^
>>> SIKIResSim.c:13835:18: note: in expansion of macro ‘COMP_GETPAR3’
>>> 13835 | int *index_ptr=COMP_GETPAR3(Res_sample, res_sample_comp, compindex);
>>> | ^~~~~~~~~~~~
>>>
>>> ==================================
>>>
>>> This is how I use TOFRes_sample() and Res_monitor():
>>>
>>> ==================================
>>>
>>> SPLIT COMPONENT RSsample = TOFRes_sample(
>>> thickness = sample_r-0.0001,
>>> radius = sample_r,
>>> yheight = sample_h,
>>> focus_xw = Wdx+0.001,
>>> focus_yh = Wdy+0.001,
>>> target_x = sample_det_x,
>>> target_y = sample_det_y,
>>> target_z = sample_det_z,
>>> time_bin = (ts+tsd+toffset)*1e6,
>>> time_width = Dtsd*1e6
>>> ) AT (0,0,L1) RELATIVE mod
>>>
>>> COMPONENT det_pos = Arm()
>>> AT (sample_det_x,sample_det_y,sample_det_z) RELATIVE RSsample
>>> ROTATED (0,atan(sample_det_x/sample_det_z)*RAD2DEG,0) RELATIVE RSsample
>>>
>>> COMPONENT resmonitor = Res_monitor(
>>> res_sample_comp = RSsample,
>>> options = "cylinder",
>>> xwidth = Wdx, yheight = Wdy,
>>> filename = "resmonitor.dat"
>>> ) AT (0,0,0) RELATIVE det_pos
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>>>
>>>
>>> Peter Kjær Willendrup
>>> Forskningsingeniør, Specialkonsulent
>>>
>>> DTU Physics
>>> [image001.gif]
>>>
>>>
>>> Technical University of Denmark
>>>
>>>
>>> [image002.gif]
>>>
>>>
>>> Department of Physics
>>> Fysikvej
>>> Building 307
>>> DK-2800 Kongens Lyngby
>>>
>>> Main office at
>>> ESS DMSC
>>> COBIS, Ole Maaløes vej 3, 2200 København N, Denmark
>>>
>>> Direct +45 2125 4612
>>> Mobil +45 2125 4612
>>> Fax +45 4593 2399
>>> pkwi at fysik.dtu.dk<mailto:pkwi at fysik.dtu.dk <mailto:pkwi at fysik.dtu.dk <mailto:pkwi at fysik.dtu.dk>>>
>>>
>>>
>>> Peter Kjær Willendrup
>>> Forskningsingeniør, Specialkonsulent
>>>
>>> DTU Physics
>>> [image001.gif]
>>>
>>>
>>> Technical University of Denmark
>>>
>>>
>>> [image002.gif]
>>>
>>>
>>> Department of Physics
>>> Fysikvej
>>> Building 307
>>> DK-2800 Kongens Lyngby
>>>
>>> Main office at
>>> ESS DMSC
>>> COBIS, Ole Maaløes vej 3, 2200 København N, Denmark
>>>
>>> Direct +45 2125 4612
>>> Mobil +45 2125 4612
>>> Fax +45 4593 2399
>>> pkwi at fysik.dtu.dk
>>>
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>
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