touschek_scatter

[marlibgin]

Aimin thanks for your answer, I have tried the way you suggest, i.e. by putting a
&insert_elements after &run_setup but I still elegant complains with a

error: Momentum aperture file ends earlier than required

frustrating to say the least ... I attach the latest version of my files,
touscat_A.ele produces the mmap file
touscat_B.ele should be used to produce the tscattering effect, but it fails ...

Of course, and depending on your time, I would be grateful if you could run and see why this fails,
but as away to proceed I suggest also this:
in the example you sent me few posts ago (aps.ele, aps.lte, momentum_aperture.mmap) the missing "link" to me, is
how you generate the .mmap file. Would you be so kind to post it?

I need to mimic the way you produce the mmap with the same TSCATTER elements
Another question, is there a way to see where these TSCATTER element are disseminated after they have been introduced with &insert_Elements?

kind regards
Marco

[marlibgin]

Dear Aimin
I re-iterate the final question of my previous post:
Would it be possible to see how you generate the momentum_aperture.mmap file related to the touschek_scatter example?

Thanks a lot in advance
Marco

[xiaoam]

Macro,

Finally understand what causes your trouble.
In the calculation of momentum_aperture, use
include_name_pattern = TEST, (result momentum aperture output at tscatter element)
don't use include_name_pattern = TS*[ABCD] (this gives you momentum aperture at element with different name and type even at the same location)

Or just use "match_position_only = 1" in your touschek simulation block. I will change the code from bomb out message to warning message.

Sorry about trouble and hope this time you will get it run smoothly.

aimin

[marlibgin]

Thanks a lot Aimin
to look carefully at this problem, it seems to work now,
I am trying to familiarize with the ouput at the moment. I understand several .out files are generated each one corrresponding to the TSCATTER element where touschek scattering process has been generated. The sFrequency correpsonds to the n. of particle/s/m lost due to a touschek process, and their loss position is shown.
I am a bit confused on how to extract the information on the losses/s around the ring, and the role of the .los files
and .dis files.

[marlibgin]

Hi all,
the touschek_scatter output shows the number of particles lost per second per meter. In other words the ring is binned in 1m sections and for every bin the number of losses is shown. Would it be possible to have the number of losses at the point where they occur? E.g. I'd like to see the number of losses per second caused by a collimator, in that point not in the 1m bin surrounding it. Thanks all for any suggestion ...

Marco

[tiansk]

Dear all,

I am using touschek_scatter Elegant command to get the beam loss rate and location from touschek scattering. But, I am not sure the meaning of results. Does anybady knows the relationship of TRate and LRate in the .los and .bun files. 'NScatter' is the sum of TRate in the corresponding file and the 'SLocalRate' is the sum of LRate. Besies that, the NScatter seems to be related to the bunch frequency while the 'SLocalRate' not. What's the exact meaning and units of these values?

Thanks a lot.

SaiKe Tian

[xiaoam]

Macro:
You can change the bin size using "sbin_step" options, for example "sbin_step=0.1", in this case the output units should be particles/second/bin.
If you want a detail loss information, you should use "STRING loss = NULL;" option, then you get a file saved all lost simulated particles. Note: particles are weighted, i.e. the total loss=sum(TRate).

Saike:
In bunch output:
The LRate is the Touschek scattering rate at the TSCATTER element location for each associated simulated particles. It's not scaled with bunch repetition rate since it's not used for total loss calculation.
The TRate is the SUM of Touschek scattering rate between the two adjacent TSCATTER elements for each associated simulated particles. Since it's used for counting total loss information, it's multiplied by bunch repetition rate or bunch frequency. Thus,
NScatter*(1-ignored_protion)=NScatter-IgnoredRate=sum(TRate) --- with bunch repetition rate
SLocalRate*(1-ignored_protion)=sum(LRate) --- without bunch repetition rate
The .los is just a subset of .bun for particle lost.

aimin

[tiansk]

Dear Aimin，

Thank you very much for your reply. It helps me alot. For every macor particle, the 'LRate' represents the particle loss per second per meter, and 'TRate' means the particle loss per second in the section between TScatter(i-1) to TScatter(i). And 'TRate' has considered the bunch frequency. Is this right?
Besides that, I have read your article of 'Monte carlo simulation of Touschek effect' for many times and you mentioned 'N' the total number of simulated scattering event and 'M' the total number of particles with energy deviation abs(delta)>delatm. In the elegant code, the parameter 'n_simulated' is the 'N' (or 'N'/2) in the article, isn't it? And how could I know or set 'M' in the code? I used to think that the 'NScatter' in the '.bun' file equals the 'M' mentioned. But recently, I found the information in file '.bun' is the particles safisfing the 'ignored_portion'(if 'ignored_portion==0', all the particles will be included in the '.bun' file).

Thanks a alot!

Saike Tian