Feedthrough Meeting 20/10/97 present: P. Birney, M. Fincke-Keeler, T. Hodges, R. Keeler, M. Lefebvre, P. Poffenberger - Comments from the Review and weld tests Terry commented on the main points of the feedthrough review that was held in CERN on October 13. Terry presented the 3 options that were retained concerning the welding of the pin carriers to the flanges. We have proposed to produce blanks and to do weld tests of up to two of the three options. Comments from welders, the quality of the welds and the resulting deformation of the flanges should be considered. The aim is to report on this activity at the next LARG week starting Dec 8th. Terry to ask Roy to produce some sketches to be used in discussion with welders, and to produce blanks. Input from TRIUMF welders will be sought this week, with a view to start machining as soon as possible, which might be just after the open house scheduled for this coming weekend (Oct 25-26). Michel to have 10 copies made of the transparencies shown at the review. - Leak Test Setup Paul proposed that we should set up a dedicated meeting to review the leak test setup capabilities, operation, its stand and the floor space. Michel agreed to set up the meeting. Pof to check on the leak checker order status [done, shipping date next week]. Margret to check the testbox demo kit status, and to look into the order for the calibration cable kit. - Vacuum Cables Michel reported in a previous email of some comments that were made at the review. See attached task list and comments. We are awaiting comments from Radeka on the connector design. Michel to phone Radeka to find out if he as received the info on the connector design, and to inform him of our short term plans concernign a prototype, if the design is adequate. Margret to talk to Ernie about a trip to Toronto to visit the vacuum cable company Strataflex - Update on project schedule Michel briefly reported on the project scedule plans, as of the review. These were agreed with our colleagues from BNL. Details can be found in the review transparency copies. The aim is to converge by Nov 15th on a final desing for prototyping, in consultation with our BNL colleagues. This would then lead to an order of pin carriers by December 15th, from Glasseal. It was mentioned that we should perhaps also order a few PCT pin carriers. It was felt that we should aim at a visit of the Glasseal company before Xmas. Michel to discuss this with Rahm. - ATLAS meetings and other important dates - Nov 09 - Nov 14 : CALOR97 Calorimetry Conference, Tucson - Nov 17 - Nov 21 : Overview ATLAS week - Dec 08 - Dec 12 : LARG week - Jan 26 - Jan 30 : LARG week - Feb ?? - Feb ?? : Lake Louise Winter Institute - Mar 02 - Mar 06 : ATLAS week - Mar 09 - Mar 13 : LARG week - Mar 24 - Apr 04 : ATLAS Physics workshop, Grenoble - May 04 - May 10 : LARG week - Jun 08 - Jun 12 : ATLAS week - Jul 06 - Jul 10 : LARG week - Jul 23 - Jul 29 : ICHEP98 "Rochester Conference", TRIUMF - Sep 04 - Sep 18 : ATLAS week - Sep 21 - Sep 26 : LARG week - Nov 12 - Nov 18 : LARG week - Nov 16 - Nov 20 : ATLAS week ACTION LIST FOR VACUUM CABLE PROJECT From meeting in CERN held Friday October 10th 1997 11:00. Present: Fincke-Keeler, Hodges, Lefebvre, Oakham, O'Neill We have established the following task item list for the vacuum cable project: 1- Margret and Michel to check with V. Radeka and C. De La Taille about electrical constraints. Report to Ernie and Gerald. [After some discussion with Christophe De La Taille and Bille Cleland, it appears that a difference of 50 milliohms between the traces would be a maximum desired. Using the 0.2ns total length difference proposed in Ernie's proposal, this corresponds to about 40milliohms of ohmic resistance difference. We are awaiting some formal reply. Magret and I should keep the pressure to get answers from the electronic convenor. This question was sent to the electronic convenors, and was clearly presented at the feedthrough review.] 2- Ernie and Gerald to provide cost estimates to Michel separating the setup cost and the unit cost, for prototypes. 3- Michel to give green light for the production of prototypes, specifying how many. 4- Prototype made before Xmas or ASAP or Ernie and Gerald to let Michel know by when they can be made. 5- Michel to try to obtain broken pin carriers from BNL. Get at least 2 so that one can be sent to Carleton. [Initial discussion done with Rahm. Looks promising.] 6- Terry to let Ernie know about any changes approved on the pin carrier design, so that the connector can adapt. 7- Michel to ask Radeka about who is responsible for signing for the vacuum cable design. Request what is the likely time required for approval. 8- Initiate discussions to find out who finally signs the feedthrough components. 9- Michel to talk to V. Vuillemin at the group meeting about convening the pigtail lengths. [Vincent agreed, his name was mentioned at the review] 10-Margret to call Ernie for comments from BNL if any. From lefebvre@uvic.ca Tue Oct 21 08:50:33 1997 Date: Thu, 16 Oct 1997 01:23:31 -0700 (PDT) From: Michel Lefebvre To: Terry Hodges , Margret Fincke-Keeler , Morley O'Neill , Gerald Oakham , Ernie Neuheimer , Richard Keeler Cc: Paul Birney , Bob Kowalewski , Paul Poffenberger , Randy Sobie , Roy Langstaff Subject: Some comment son vacuum cables Greetings. During the feedthrough review that took place Monday 13th October at CERN, I have gathered the following comments pertaining to the vacuum cable. Please comments if needed! Regards Michel - Is the proposed wire mesh method used in other HEP applications for connectors? The question here raises the question of experience using such an approach, and if it has been used before in similar conditions. This question was raised by Howard Gordon. - Pierre Pailler pointed out that perhaps, upon assembly, a strand of the wire mesh could puncture the Kapton. Do you believe that it is a concern? How can we prove it is not? Perhaps a close up picture of a wire mesh used could reveal whether or not there are such badly oriented strands. - Christophe De La Taille asked what was the Kapton thickness between the two signal traces. Remember that the two strips face each other signal-to-signal. The previous design from BNL (what was the thickness used?) was tested and the crosstalk induced measured to be not a problem. What do we plan? Perhaps we should just use the same thickness as used before for now. - The question was raised again whether or not the connector fits the pin carrier. It was mentionned by C.De La Taille that it is understood to be easy to modify the mold for the connector. Remember that we have agreed that Terry would communicate ASAP any knowledge of a modification of the pin carrier that could result in a change for the connector fitting (I suspect there won't be any). - Concerning the allowed dispersion in strip lengths, we have used the 0.2ns mentioned by Ernie, from which Margret and Terry have calculated a corresponding dispersion in ohmich resistance of 40 milliohms. Please confirm/update these numbers ASAP. If different from above, we should let Radeka and De La Taille know immediately. From back stage discussions, I have found out that variations of 100milliohms in the signal paths on the calibration cards had to be compensated by hardware in the calibration cards... which means that we should stay probably below 50milliohms if we want to please the Orsay team. The time delay dispersion I feel should not be a problem... rumours go that at the moment up to 2ns time dispersion are found in pigtails of the same physical length (6 meters)... though this is supposed to improve. This tells me that the timing difference resulting in strip length difference in our short strip line will be a minor contribution to the overall time dispersion up to the crate, as long as we keep it small (0.2ns?). From ernie@hincks.physics.carleton.ca Tue Oct 21 08:50:50 1997 Date: Thu, 16 Oct 1997 15:54:23 -0400 (EDT) From: Ernie Neuheimer To: Michel Lefebvre Cc: Terry Hodges , Margret Fincke-Keeler , Morley O'Neill , Gerald Oakham , Richard Keeler , Paul Birney , Bob Kowalewski , Paul Poffenberger , Randy Sobie , Roy Langstaff Subject: Re: Some comment son vacuum cables Michel: I would like to reply to some of the comments raised at your review of the vacuum cable feedthroughs as attached below: 1- The wire mesh was proposed by Radeka and Makowieki at Brookhaven this summer. I (and Gary Hoeppel of Strataflex) suggested a conductive elastomeric strip. I assume it was declined for reasons of poor elasticity at low temperature, vacuum pumping and radiation hardness. 2- Signal-to-ground shorts would be picked up by 100% testing of cables after final assembly. 3- Signal trace separation between facing strips is nearly the same as the Brookhaven rigid-flex cable (.114" for flex cable design vs .132" for the rigid-flex design) at the connector "entrance", a difference of .018". 4- I would welcome receiving "broken" pin carriers to try prototype connector assemblies for mechanical fit. 5- My estimate of the maximun signal trace length difference between inner-most (shorter) and outer-most (longer) traces in a symmetrical layout is based on rough measurements with a ruler. Unless the requirements of additional press plate screw holes force the routing of traces much differently, I don't forsee any change in this path length difference. Ernie. PS: I have not heard any comments from Brookhaven or received a cost estimate for prototype manufacture from Strataflex.