From ovidiu at umich.edu Fri Oct 3 09:21:40 2008 From: ovidiu at umich.edu (Toader, Ovidiu) Date: Fri, 3 Oct 2008 09:21:40 -0400 Subject: [Sneap] SNEAP 2008 - Last Call? Message-ID: <2FC6BC86AB61614A992FFC024EABC281019C5103@ECLUST2-VS4.adsroot.itcs.umich.edu> Greetings! Here we are about 10 days away from our SNEAP 2008 meeting! If you are considering coming but are not sure yet please let me know so I can get the final numbers for logistics purposes. I am sure we will be able to help you find accommodations in Ann Arbor if that proves to be a problem. We look forward to seeing you here! Regards, Ovidiu ****************************************************** Ovidiu Toader, Manager Michigan Ion Beam Laboratory, University of Michigan, 2600 Draper Rd. Ann Arbor MI 48109 http://www-ners.engin.umich.edu/research/Mibl ovidiu at umich.edu (734) 936-0166 ****************************************************** Ex nihilo nihil ... (Parmenides) ****************************************************** -------------- next part -------------- An HTML attachment was scrubbed... URL: http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20081003/3aaa103a/attachment.html From cwest at tunl.duke.edu Thu Oct 23 15:45:35 2008 From: cwest at tunl.duke.edu (Chris Westerfeldt) Date: Thu, 23 Oct 2008 15:45:35 -0400 Subject: [Sneap] Posting: Request for information Message-ID: SNEAPers, I am posting this for Mr. Davidson at Sandia. If you have any information related to his inquiry, please reply either to the list or directly to Mr. Davidson at Sandia. Thanks, - Chris +++ I am trying to determine whether a Van De Graaff accelerator (or similar if there are other things) test capability exists at Sandia. I am not aware of any capability like that here. Would you know, or know of people I could contact to check. We have worked with a facility at Concordia college in Moorhead MN that has such an accelerator, but did not have much success with the tests. These accelerators are typically used to accelerate micron sized iron particles to km/sec velocities for impact testing. I was told that you would be someone that would be familiar with our capabilities in that area. Thanks, Daren Daren L. Davidson Sandia National Laboratories Aerospace Systems Development, Lethality and Threat Dept. 1515 Eubank SE, mail stop 1185, Albuquerque, NM 87123 ph 505-844-3124 fax 505-844-0094 email: dldavid at sandia.gov -- Chris R. Westerfeldt Research Scientist / T.U.N.L. Radiation Safety Manager Duke University Physics Department & Triangle Universities Nuclear Laboratory Science Drive, Box 90308 Durham, NC 27708-0308 Tel: (919) 660-2600 Fax: (919) 660-2634 Email: Cwest at Tunl.Duke.Edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20081023/b0a72294/attachment.html From gharper at u.washington.edu Thu Oct 23 16:15:09 2008 From: gharper at u.washington.edu (ThunderHooves) Date: Thu, 23 Oct 2008 13:15:09 -0700 (PDT) Subject: [Sneap] Posting: Request for information In-Reply-To: Message-ID: Barney Doyle used to head the facility at Sandia. At one time they had an EN tandem and a couple of 2MV single ended machines. Gregory C. Harper Phone:(206) 543-4084 (Office) Research Engineer/Scientist IV (206) 543-4062 (Lab) University of Washington FAX: (206) 685-4634 CENPA NPL Bldg. Box 354290 email: gharper at u.washington.edu Seattle, WA 98195-4290 On Thu, 23 Oct 2008, Chris Westerfeldt wrote: > The host for the 2008 SNEAP annual meeting is the University of Michigan at Ann Arbor. The meeting dates are: October: 12 - 17, 2008. > The meeting web link is: http://www-ners.engin.umich.edu/research/Mibl/Sneap/2008.htm > > From bdarling at jpaw.com Thu Oct 23 17:04:50 2008 From: bdarling at jpaw.com (bdarling at jpaw.com) Date: Thu, 23 Oct 2008 17:04:50 -0400 Subject: [Sneap] Posting: Request for information Message-ID: <380-22008104232145039@M2W032.mail2web.com> Contact Larry Rowton at Los Alamos Lab. He was head of the facility at LANL that used the vertical VDG for micrometeorite studies [since closed], and he should certainly know if anyone does that at Sandia. Bob Original Message: ----------------- From: Chris Westerfeldt cwest at tunl.duke.edu Date: Thu, 23 Oct 2008 15:45:35 -0400 To: sneap at tunl.duke.edu Subject: [Sneap] Posting: Request for information The host for the 2008 SNEAP annual meeting is the University of Michigan at Ann Arbor. The meeting dates are: October: 12 - 17, 2008. The meeting web link is: http://www-ners.engin.umich.edu/research/Mibl/Sneap/2008.htm -------------------------------------------------------------------- mail2web - Check your email from the web at http://link.mail2web.com/mail2web From gunther at cathode.com Tue Oct 28 14:16:36 2008 From: gunther at cathode.com (Kim Gunther) Date: Tue, 28 Oct 2008 11:16:36 -0700 Subject: [Sneap] Thomson CIRCE 2 Gun Message-ID: We are looking for a gun spec, tube spec, drawing, fimalent detail, gasket details, etc., on an old gun we have. This is what we know: Thomson CIRCE 2 food sterilization accelerator Univ. Iowa may have similar system from the '90s filament may be B16050003 filament ~10V 28-33A running, 18A warmup. if anyone has any leads, we would appreciate it. Best regards Kim Gunther HeatWave Labs ( 831-722-9081 6 831-722-5491 8 gunther at cathode.com ? www.cathode.com -------------- next part -------------- An HTML attachment was scrubbed... URL: http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20081028/da083bc0/attachment.html From cwest at tunl.duke.edu Wed Oct 29 11:55:44 2008 From: cwest at tunl.duke.edu (Chris Westerfeldt) Date: Wed, 29 Oct 2008 11:55:44 -0400 Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue Message-ID: Here is an interesting problem that I believe has been present since the accelerator here was installed. When I came here in 1989 people just pumped out the tank without watching the LE and HE vacuums. When filling the tank they would watch both gauges for any pressure leaks. In 1991 I began recording the vacuums when people pumped out. Lo and behold, at around 50-70 psig the HE vacuum would go from low 10-7 to low 10-6 range and then slowly return to low 10-7 once the tank was pumped out. When tank was pressurized all was okay. I mentioned this to several people that we need an RGA, as I think there was a small tank gas leak that briefly opens when pumping out. Nobody paid any attention to me. Fast forward to this year. Lo and behold a used RGA appeared. I put a head on the HE and waited for a tank pumpout, like yesterday. Bingo, while taking scans as we pumped out suddenly at about 70 psig the HE vacuum went up to 1.5 X 10-5 and began coming down again slowly. My scans showed a big N2, a smaller CO2, and very small SF6 peaks?. tank gas components. Another scan ? hour showed no SF6, and the N2 and CO2 peaks were smaller while the vacuum was in the low 10-6 range. Interestingly, by the time the tank was vented the vacuum was still 2 X 10-6, but the N2 and CO2 peaks were about the same size now. By this morning the vacuum was still 1.1 X 10-6, instead of low 10-7, and the CO2 peak was 3 times as big as the N2 and H2O peaks. In fact, valving off the cryopump causes the CO2 peak to grow really big! As though there is a gaseous CO2 source somewhere in the vacuum system. Over a long period of time, days-weeks, the vacuum will improve as the CO2 peak slowly drops. I suspect something briefly opens up at 70 psig, lets some tank gas in briefly that fills up some reservoir within the HE part of accelerator vacuum system and that leaks the N2 fairly quickly away but retains the CO2 over a much longer time frame as it very slowly gets pumped away over a period of days-weeks, finally returning to a low 10-7 range. Do not see this in the LE, hoping to install another RGA there soon. Helium leak check in air of HE of accelerator found nothing. Testing of stripper gas found only Argon and went away when leak valve closed off. It?s almost like a big sponge in the vacuum system that sucks up a lot of the CO2 that briefly leaks in and then slowly releases it over a very long period of time. Obviously need to locate the source of the brief leak. I think this has been happening since day 1. Any thoughts, ideas???? If not, can you pass it on to the SNEAP community for their thoughts? Thanks a bunch. Cheers!!!! ? Tom Miller -- Chris R. Westerfeldt Research Scientist / T.U.N.L. Radiation Safety Manager Duke University Physics Department & Triangle Universities Nuclear Laboratory Science Drive, Box 90308 Durham, NC 27708-0308 Tel: (919) 660-2600 Fax: (919) 660-2634 Email: Cwest at Tunl.Duke.Edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20081029/fd394b91/attachment.html From diwill at u.washington.edu Wed Oct 29 14:27:30 2008 From: diwill at u.washington.edu (Douglas I Will) Date: Wed, 29 Oct 2008 11:27:30 -0700 (PDT) Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue In-Reply-To: Message-ID: CO2 is very soluble in most rubber and other hydrocarbon compounds. Most o-rings absorb CO2 from tank gas. They can easily behave like a sponge. Doug Will U of Washington Center for Experimental Nuclear Physics and Astrophysics From kgb at phys.au.dk Wed Oct 29 14:16:27 2008 From: kgb at phys.au.dk (Klaus Bahner) Date: Wed, 29 Oct 2008 19:16:27 +0100 Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue In-Reply-To: Message-ID: <200810291816.m9TIGRYf012068@mfe02.daimi.au.dk> Tom, We see similar effects (i.e. changes in vacuum on both HE and LE side) when venting or filling our EN. Those changes in vacuum are not very predictable, sometimes it's only seen on HE, sometimes only on LE. Our explanation - without any hard proof for it - is that the length change of the accelerator vessel when pressurizing or venting the tank cause movements of the column and hence movements of the acceleration tubes, causing small "leaks" at the O-ring seals. I monitored for example the vertical position of the stripper channel during pressure changes and found out that it significantly sagged (if I remember it correctly order of 1mm) when the tank is pressurized and lifted again, when pumped out. Whether this is just coincidence or not, I'm not sure about, but when we replaced our acceleration tubes some years ago, we replaced the O-rings inside the tank with Buna O-rings instead of Viton O-rings and since then, the effects were not as much pronounced as before. I tend to regard the Buna as the improvement, but it is of course also possible that we were just lucky and the tubes and bellows fit a bit better than before. With regard to your CO2 question, does anybody know the absorption/outgassing rate of CO2? At least I wonder wether the assumed reservoir on your HE side is the acceleration tube itself. Considering how long it takes to pump down acceleration tubes, once they were exposed to air, I think degassing would be a possibility. Admittedly the long pump down times of acceleration tubes are usually associated with water vapor. I don't know whether it is difficult in general to get rid of absorbed CO2 or not, still I would consider this an option. Regards, Klaus -------------------------------------------- AMS 14C Dating Centre Aarhus University Ny Munkegade, Byg. 1520 DK - 8000 Aarhus C Phone: +45 8942 3736 Fax: +45 8612 0740 -------------------------------------------- _____ From: sneap-bounces at tunl.duke.edu [mailto:sneap-bounces at tunl.duke.edu] On Behalf Of Chris Westerfeldt Sent: 29. oktober 2008 16:56 To: SNEAP Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue Here is an interesting problem that I believe has been present since the accelerator here was installed. When I came here in 1989 people just pumped out the tank without watching the LE and HE vacuums. When filling the tank they would watch both gauges for any pressure leaks. In 1991 I began recording the vacuums when people pumped out. Lo and behold, at around 50-70 psig the HE vacuum would go from low 10-7 to low 10-6 range and then slowly return to low 10-7 once the tank was pumped out. When tank was pressurized all was okay. I mentioned this to several people that we need an RGA, as I think there was a small tank gas leak that briefly opens when pumping out. Nobody paid any attention to me. Fast forward to this year. Lo and behold a used RGA appeared. I put a head on the HE and waited for a tank pumpout, like yesterday. Bingo, while taking scans as we pumped out suddenly at about 70 psig the HE vacuum went up to 1. 5 X 10-5 and began coming down again slowly. My scans showed a big N2, a smaller CO2, and very small SF6 peaks?. tank gas components. Another scan ? hour showed no SF6, and the N2 and CO2 peaks were smaller while the vacuum was in the low 10-6 range. Interestingly, by the time the tank was vented the vacuum was still 2 X 10-6, but the N2 and CO2 peaks were about the same size now. By this morning the vacuum was still 1.1 X 10-6, instead of low 10-7, and the CO2 peak was 3 times as big as the N2 and H2O peaks. In fact, valving off the cryopump causes the CO2 peak to grow really big! As though there is a gaseous CO2 source somewhere in the vacuum system. Over a long period of time, days-weeks, the vacuum will improve as the CO2 peak slowly drops. I suspect something briefly opens up at 70 psig, lets some tank gas in briefly that fills up some reservoir within the HE part of accelerator vacuum system and that leaks the N2 fairly quickly away but retains the CO2 over a much longer time frame as it very slowly gets pumped away over a period of days-weeks, finally returning to a low 10-7 range. Do not see this in the LE, hoping to install another RGA there soon. Helium leak check in air of HE of accelerator found nothing. Testing of stripper gas found only Argon and went away when leak valve closed off. It?s almost like a big sponge in the vacuum system that sucks up a lot of the CO2 that briefly leaks in and then slowly releases it over a very long period of time. Obviously need to locate the source of the brief leak. I think this has been happening since day 1. Any thoughts, ideas???? If not, can you pass it on to the SNEAP community for their thoughts? Thanks a bunch. Cheers!!!! Tom Miller -- Chris R. Westerfeldt Research Scientist / T.U.N.L. Radiation Safety Manager Duke University Physics Department & Triangle Universities Nuclear Laboratory Science Drive, Box 90308 Durham, NC 27708-0308 Tel: (919) 660-2600 Fax: (919) 660-2634 Email: Cwest at Tunl.Duke.Edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20081029/967a47c1/attachment-0001.html From nick at louisiana.edu Wed Oct 29 16:20:44 2008 From: nick at louisiana.edu (Nicholas Pastore) Date: Wed, 29 Oct 2008 15:20:44 -0500 Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue In-Reply-To: Message-ID: <0705C378CE494496AC15B1BA46535D14@win.louisiana.edu> Tom, In addition to the o-rings absorbing CO2, you might have a recirculation pump connected to your stripper canal with a filter attached to it that would likely absorb CO2 better than N2 or other types of gas. It is recommended that such filters be baked out periodically. Nick ______________________ Nicholas Pastore Operations Manager Louisiana Accelerator Center UL Lafayette ______________________ Message: 1 Date: Wed, 29 Oct 2008 11:55:44 -0400 From: Chris Westerfeldt Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue To: SNEAP Message-ID: Content-Type: text/plain; charset="iso-8859-1" Here is an interesting problem that I believe has been present since the accelerator here was installed. When I came here in 1989 people just pumped out the tank without watching the LE and HE vacuums. When filling the tank they would watch both gauges for any pressure leaks. In 1991 I began recording the vacuums when people pumped out. Lo and behold, at around 50-70 psig the HE vacuum would go from low 10-7 to low 10-6 range and then slowly return to low 10-7 once the tank was pumped out. When tank was pressurized all was okay. I mentioned this to several people that we need an RGA, as I think there was a small tank gas leak that briefly opens when pumping out. Nobody paid any attention to me. Fast forward to this year. Lo and behold a used RGA appeared. I put a head on the HE and waited for a tank pumpout, like yesterday. Bingo, while taking scans as we pumped out suddenly at about 70 psig the HE vacuum went up to 1.5 X 10-5 and began coming down again slowly. My scans showed a big N2, a smaller CO2, and very small SF6 peaks?. tank gas components. Another scan ? hour showed no SF6, and the N2 and CO2 peaks were smaller while the vacuum was in the low 10-6 range. Interestingly, by the time the tank was vented the vacuum was still 2 X 10-6, but the N2 and CO2 peaks were about the same size now. By this morning the vacuum was still 1.1 X 10-6, instead of low 10-7, and the CO2 peak was 3 times as big as the N2 and H2O peaks. In fact, valving off the cryopump causes the CO2 peak to grow really big! As though there is a gaseous CO2 source somewhere in the vacuum system. Over a long period of time, days-weeks, the vacuum will improve as the CO2 peak slowly drops. I suspect something briefly opens up at 70 psig, lets some tank gas in briefly that fills up some reservoir within the HE part of accelerator vacuum system and that leaks the N2 fairly quickly away but retains the CO2 over a much longer time frame as it very slowly gets pumped away over a period of days-weeks, finally returning to a low 10-7 range. Do not see this in the LE, hoping to install another RGA there soon. Helium leak check in air of HE of accelerator found nothing. Testing of stripper gas found only Argon and went away when leak valve closed off. It?s almost like a big sponge in the vacuum system that sucks up a lot of the CO2 that briefly leaks in and then slowly releases it over a very long period of time. Obviously need to locate the source of the brief leak. I think this has been happening since day 1. Any thoughts, ideas???? If not, can you pass it on to the SNEAP community for their thoughts? Thanks a bunch. Cheers!!!! ? Tom Miller -- Chris R. Westerfeldt Research Scientist / T.U.N.L. Radiation Safety Manager Duke University Physics Department & Triangle Universities Nuclear Laboratory Science Drive, Box 90308 Durham, NC 27708-0308 Tel: (919) 660-2600 Fax: (919) 660-2634 Email: Cwest at Tunl.Duke.Edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20081029/fd394b91/a ttachment-0001.html From akc103 at rsphysse.anu.edu.au Wed Oct 29 16:54:26 2008 From: akc103 at rsphysse.anu.edu.au (akc103 at rsphysse.anu.edu.au) Date: Thu, 30 Oct 2008 07:54:26 +1100 (EST) Subject: [Sneap] Interesting Problem -- posted for Tom Miller at Purdue In-Reply-To: References: Message-ID: <62571.68.35.248.194.1225313666.squirrel@wwwrsphysse.anu.edu.au> >Hi, The ANU accelerator tube changes about a range during pump out and gas up. We have leak chased repeatedly over the years and still can't explain it. We have wire gaskets and the column is independent of vessel growth due to pressure so it is very puzzling. Maybe when we have our old RGA running again then we can look for gas peaks. Still wondering for now. Cheers, Al