-------- Original Message -------- Subject: summary "cooling for BGV" Date: Fri, 14 Mar 2014 09:59:11 +0100 From: Massimiliano Ferro-Luzzi To: Michele Battistin CC: Bernd Dehning Dear Michele, please find below the email that I exchanged with Julabo on the question of radiation tolerance. It's very succinct. I did not ask anything about possible separation of sensitive parts from the mechanical device. The maximum expected radiation is indeed in the order of 20Gy/year (I also attach a mail from Plamen which describes how he arrives at this number). As a summary of today's dicussion (comments welcome!): - As an alternative to the transfer line solution, a custom solution was discussed which seems more attractive in terms of cost and complexity. The proposal is to install the refrigerating unit inside the LHC tunnel (upstream of the BGV, under the beam pipes, no problem of space), while keeping the control electronics (sensitive to radiation) in the service tunnel. - EN-CV will investigate whether a company (Julabo, Huber ?) can provide such a solution (but it's quite unlikely). - If the answer is negative, EN-CV will propose a home-made solution, based on commercial components with which EN-CV has already substantial experience. - In about 1-2 weeks, reconvene to discuss a first draft of schematics of the cooling system, with possibly a preliminary list of components and cables. - Massi: re-draft the BGV cooling specs to take into account the newly proposed solution. - It was remarked that the 60m cable installation (between BGV location and racks) will take place from mid April to mid May. - A test of the cooling system with actual BGV modules would be very useful and could take place around september. cheers Masi ------------------------------------------------------------ ------------------------------------------------------------ ---------- Forwarded message ---------- Date: Thu, 12 Dec 2013 14:41:24 +0100 From: "Herrling, Felix" To: Massimiliano.Ferro-Luzzi@cern.ch Subject: AW: radiation resistance Dear Massimiliano Ferro-Luzzi, I have checked it but we don’t have any special protection against radiations. We don’t have done any tests in an environment like this. It is not possible to remove and replace the electronic, you can only work with a distance of 20m with long pipes from our unit to your application. ------------------------------------------------------------ ------------------------------------------------------------ Dear Dr Herrling as agreed this morning on the phone, I send you here some more information on my cooling unit application and on my question. We would like to use a monophase liquid cooling device to cool a photon detector (Silicon photo-multiplier) to approximately -40 C with a total cooling capacity of the order of 150W. The detectors are near the Large Hadron Collider beam pipe, where radiation (at a distance of about 0.5 m) can be as high as 1-10 krad/year ( = 10-100 Gy/year). Not very high, but sufficient to make standard commercial electronics to fail. Would you have cooling units that are suitable for such an environment ? For example, we have been considering the F81-HL device. Would its electronics function in such an environment ? If not, would it be possible to remove and place the electronics unit at a distance of about 20m (behind a large shielding wall) with a cable connection ? many thanks best regards MFL ------------------------------------------------------------ ------------------------------------------------------------ Hi Massi, today we discussed briefly with Bernd a possible approach to determine the expected dose at the location of the BGV cooling chiller. Assumptions: - the chiller will be located 2-3 meters upstream of the gas tank - the BGV pressure bump will have negligible effect In this case we can use the measurements of the BLMs located close to (but not shielded by) the Quadrupoles. The material/geometry layout is different from our case, but we think this way we can get the right order of magnitude for the radiation dose. I checked the doses measured in 2012 of 2 such BLMs: BLMQI.06L4.B1I30_MQY and BLMQI.06L4.B2E30_MQY. The dose values are quite similar for the two monitors. The maximal monthly dose is about 0.5 Gy (assuming BLMs offset of 3.e-7 Gy/s), so I think we can assume 1 Gy/month for beam intensity of 2.e14 protons. Then, scale up by 10 (months) and by 2 (beam intensity). We get O(20) Gy/year. In my previous email I wrote that there might be a RadMon located before the DFB (in front of the door-grid), whose measurements we can use. Now I checked the layout database and I don't see a RadMon at this location, so this is not a possibility anymore. Cheers, Plamen