Next Meeting

Date: July 29, 1997

Time: 3:00 - 4:00

Place: Bldg 89, Large Conference Room

Attendees

R. Legg, R. Evans, K Jordan, G. Neil, J. Bennett,
P. Piot, S. Benson, Q.S. Shu, R. Walker, L. Merminga

Addenda/Errata to Previous Minutes

• None.

• Kevin gave a short update on the FEL AMS system. The system will use eight 16x16 crosspoint switches from Analog Devices to allow a 128 in to 16 lines out signal selector. Kevin brought one of the boards from AD with him. It was very nice, arriving pre-connectorized (BNC's) with software to allow PC control. Kevin says the software to EPICS will use the DLPC driver written for the ITS last spring. All channels will have an RMS convertor on them with a signal into EPICS. This will allow any of the 128 signals to be archived. The RMS convertors are housed in 32 channel crates using the backplane designed for the 2 nA BPMs.
  The bandwidth of the system is limited to 1 MHz in the MCC by the fiber optic link to the FEL building, but in the FEL building the bandwidth will be greater than 5 MHz. The drawback of the system is that it has no positive verification of the channel selected, but there is a cal signal and the hardware is commercial, so reliability should be better. However, there will be extensive tests to avoid the problems observed on the AMS in the main machine. Cost looks to be within the $50K allocated with a test article available within 3 weeks, maybe.

• The QJ centering issue was discussed. The problem is simply that the QJ magnetic centers, while known very accurately with respect to the probe used, are not known well with respect to the mechanical centers since the probe is not aligned with respect to the mechanical dimensions prior to measurement. The variation of the mechanical center to the magnetic one is thought to be as much as 1-2 mm RMS from article to article. Since the magnets are aligned according to the mechanical tooling, this variation is what the electron beam will see. Yunn has been tasked with determining what the sensitivity of the beam to this offset will be. If it must be corrected, there are three options: 1) Fiducialize and align the test stand and re-measure the magnets, 2) Install enough correctors to center in every quad, or 3) Install as is and use the beam to determine quad offsets and then re-align to fit. Option 1) was rejected on schedule grounds, option 2) was rejected on cost. Presently, we will investigate the sensitivity of the effect and look at option 3).

• The first draft of a cryomodule fine phasing procedure was passed out for review. Briefly, the algorithm determines zero crossings for improved sensitivity and crest and anti-crest to check for non-linearities and give some statistics. Lia will continue reviewing the procedure and discuss a gradient calibration procedure with M. Tiefenback. These tasks are complicated by the phasing dipole limitation of about 20 MeV maximum acceptance.

• Need an "FEL Test Plan Worksheet" template if we are to avoid FEL experiments being setup on the main machine (like the cryomodule phasing one above). Legg will talk to T. Oren about fitting the document into the overall OP's scheme.

• Do we want to write a separate OSP for the new building or rewrite the OSP for the site to include the FEL building? What are the ramifications of either action? Who would know what the ramifications are? Legg suggested the M7 would be the right group to ask, since ulitimately they (or Andrew) are responsible for the site. Because of the urgency, however, we will ask T. Hassler and probably write a separate OSP for the FEL building.

• G. Neil asked and got approval to limit the N2 flow in the enclosure to 20 CFM to reduce the ODH hazard.

• Yunn needs to rerun his simulations for an "insensitive" setup for the 60 pC and 135 pC cases now that he has a solution to the long gun injector. Legg will send him a note.

Action Items
------------

• Legg send note to Yunn on "insensitive" setup.
• Legg to discuss with T. Oren new FEL template.
• Yunn will check QJ alignment sensitivity.

A-15   1  Commissioning Procedure                Legg, Krafft    7/16/97
A-19   0  Web Documentation                                      weekly
A-34   2  Consistent Linac phasing plan          Yunn
A-44  1,2 Start Rui, Jinhu? on emittance code    Douglas         8/13/97

Action Items (pending)
------------

P-05  1   Devise fine-tuning procedure for buncher gradient	Krafft/Kehne
P-08 1,2  How do we change energy? What is the energy range?	Benson
P-20  1   Lock plans (who in particular)			Johannes?
P-21  1   Save/restore plans					Benesch
P-25 1,2  RF control sensitivities/				Merminga
	    Microphonics Diff for FEL/
	    Pathlength effect
P-29  2   FEL/linac interaction					Merminga

Agenda for Next Meeting
-----------------------

          Item                              Person Responsible     Time
          ----                              ------------------     ----
*   Review agenda/corrections to minutes	  Legg	           5 min.
*   Magnet Integration Plan			 Douglas 	   30 min
*   New issues					   All		   10 min	
*   Agenda for next meeting		           All	           5 min.