[esa-t474] FW: ESA running; primary beam tests

[Woods, Michael B.]

Hi, one of the items from yesterday's t-474 meeting was to get an update on what to expect from lcls beams this year regarding charge and how beam time sharing with lcls commissioning would work.  Some exchange with Paul Emma on this is given below. 

Additional input will come after Stew and Nigel discuss their manpower available for a t474/t480 run and for the analysis.  Would also be useful to know what Michele's plans are.  It seems like Sergey will be completing his thesis, graduating and moving on from information Bino provided.  We had some discussion that if we ran we might not use the magnets for T-474, though I would find this quite perplexing for motivation as the goal is to demonstrate spectrometer performance.

We'll try to converge on a run scenario by email.  But if necessary we can have a further phone discussion Thursday at 8am slac time.  mike

-----Original Message-----
From: Woods, Michael B. 
Sent: Monday, March 03, 2008 3:49 PM
To: Emma, Paul J.
Cc: Hast, Carsten
Subject: ESA running; primary beam tests

Hi Paul, quick update on our thinking for ilc tests this spring, looking at a run in late may or early june:
1.  Minimally we want to request 1 week of beamtime in late may.  Main purpose would be to get additional data for T-487 Smith-Purcell bunch length diagnostics test.
	They want to add analyzer optics to demonstrate polarization of their signal and also want to commission fast turn-around Kramers-Kronig analysis for phase 
	retrieval.  They have rather modest demands on the beamtime and beam parameters.  Two people would come for the tests.  If they can have stable beam on owl shifts 
	at ~1nC should satisfy them.  And would want to provide a range of bunch lengths to study (I can consult with you later on setup for that).  We'd likely want to do
	some TCAV measurements to assist this.
2.  Still under discussion is to have an additional run for the bpm energy spectrometer and collimator wakefield people.  These involve more preparation and setup work 
	and have higher demands on beam parameters and stability.  If we do this it would add at least a week to the run request.  Still taking stock of people available,
	how compelling this is, etc.  Helpful to this discussion would be additional info you might be able to provide: 
		- how many hours per day can we be the primary user?  8? 12?  Can we have at least 1 weekend as primary user?
		- expected charge when we're primary user -- 1nC?  A couple shifts at higher charge of 1e10?
		- stability issues:  energy jitter, intensity jitter, phase stability, 
		- transverse emittance at end of Linac (anything at 10 mm-mrad or less is terrific for our use)

Hoping to converge on our request by end of the week (had hoped to have converged by now ...) and will be discussing with Roger E. and John Seeman etc.
Am sensitive that cumulative requests for what's described above and additional tests can be an issue, since there are also undulator damage tests and secondary beam tests for detector R&D desired.  Hopefully the secondary beam generated by parking lcls beam on Be target is not very disruptive.  I also expect the T-487 test is not very disruptive as their beam requirements are not so demanding.  
mike
	
-----Original Message-----
From: Emma, Paul J. 
Sent: Monday, March 03, 2008 9:23 PM
To: Woods, Michael B.
Cc: Hast, Carsten
Subject: RE: ESA running; primary beam tests

Hi Mike,

This all sounds quite possible, but I am not yet sure what other beam time requests will come.

- how many hours per day can we be the primary user?  8? 12?  Can we have at least 1 weekend as primary user?

	I can imagine 8-12 without much trouble.  And yes, a weekend or two will be no problem.

- expected charge when we're primary user -- 1nC?  A couple shifts at higher charge of 1e10?

	1 nC is no trouble.  Higher is possible but there are tradeoffs (we must also fully recover from April gun work).

- stability issues:  energy jitter, intensity jitter, phase stability,

	Charge jitter is <2% rms.  Energy jitter is currently 0.4% rms (50 MeV).  Phase (beam timing jitter) looks like about 0.1 deg of S-band now.  Akre fixed the phase-lock loop last week, and the effect was dramatic (was 0.5 deg rms and more)!

- transverse emittance at end of Linac (anything at 10 mm-mrad or less is terrific for our use)

	Transverse emittance is still variable (1-5 mm-mrad), but <10 mm-mrad is easy.


I hope this helps.

	Thanks,
	-PE

-----Original Message-----
From: Woods, Michael B. 
Sent: Monday, March 03, 2008 3:49 PM
To: Emma, Paul J.
Cc: Hast, Carsten
Subject: ESA running; primary beam tests

Hi Paul, quick update on our thinking for ilc tests this spring, looking at a run in late may or early june:
1.  Minimally we want to request 1 week of beamtime in late may.  Main purpose would be to get additional data for T-487 Smith-Purcell bunch length diagnostics test.
	They want to add analyzer optics to demonstrate polarization of their signal and also want to commission fast turn-around Kramers-Kronig analysis for phase 
	retrieval.  They have rather modest demands on the beamtime and beam parameters.  Two people would come for the tests.  If they can have stable beam on owl shifts 
	at ~1nC should satisfy them.  And would want to provide a range of bunch lengths to study (I can consult with you later on setup for that).  We'd likely want to do
	some TCAV measurements to assist this.
2.  Still under discussion is to have an additional run for the bpm energy spectrometer and collimator wakefield people.  These involve more preparation and setup work 
	and have higher demands on beam parameters and stability.  If we do this it would add at least a week to the run request.  Still taking stock of people available,
	how compelling this is, etc.  Helpful to this discussion would be additional info you might be able to provide: 
		- how many hours per day can we be the primary user?  8? 12?  Can we have at least 1 weekend as primary user?
		- expected charge when we're primary user -- 1nC?  A couple shifts at higher charge of 1e10?
		- stability issues:  energy jitter, intensity jitter, phase stability, 
		- transverse emittance at end of Linac (anything at 10 mm-mrad or less is terrific for our use)

Hoping to converge on our request by end of the week (had hoped to have converged by now ...) and will be discussing with Roger E. and John Seeman etc.
Am sensitive that cumulative requests for what's described above and additional tests can be an issue, since there are also undulator damage tests and secondary beam tests for detector R&D desired.  Hopefully the secondary beam generated by parking lcls beam on Be target is not very disruptive.  I also expect the T-487 test is not very disruptive as their beam requirements are not so demanding.  
mike
	
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