HI Zisis,See notes below:On Fri, 9 Mar 2007, Zisis Papandreou wrote:Hi Elton et al:following the meeting with SensL last month, we were asked toinvestigate the following, in connection to the cooling of the 4x4Sensor Arrays (SA), each consisting of 16 3x3mm2 cells.1. What are the plans for the control of temperature and humidity inHall-D? This is a civil engineering question. Can you point us toinfo on this? SensL brought up the number of <15% humidity in theHall. Is this achievable, and if not can it be made a goal?Civil design conditions for the hall are 70deg, 55% humidity.The conventional facilities design criteria can be found from you jlabaccount at the following directory:/group/planteng/12_GeV/Design/Hall_D_Design/Space_Program_Design_Criteria/Space_Program_Design_Criteria_v1-0.docI do not know how achievable the <15% humidity requirement would be inhumid Virginia, nor do I know if that is desirable. For such low levels ofhumidity other problems arise, so even considering this as a goal shouldbe thought through. For the moment, I think we need to consider optionswith our standard humidity conditions for the hall.
2. 'Global cooling' of all 4224 SAs for the BCAL was discussed. Whatare thoughts from JLab engineers on this? Can we achieve air flow,nitrogen flow, or water cooling over the SA region? We are talkingabout a doughnut-shaped enclosure for gas flow, and something elsefor liquid flow. Also, above dew point and below dew points optionsshould be discussed. With SensL we are working towards a above dewpoint option, which will still provide us with a factor ~5 decreasein the DR from cooling.Tim Whitlatch has been working on the cooling system for the FDC, but wehave also given him some numbers for the Bcal and it only makes sense todesign a single system to handle all cooling requirements inside thesolenoid.
Cooling individual SAs is expensive. SensL gave us a number of US$200 per SA (not firm, just approximate at this stage) for *bare*SAs. Adding the cooling and TEC to this, adds another US$160 to theprice. Clearly, there is strong motivation from cost (andcomplexity) in pursuing a global cooling solution. JLab needs totake the lead on this, since Regina has no engineering expertise.What do you mean by cooling individual SA's? Is this to remove the heatgenerated by the Peltier junction to the outside?
Cheers, Zisis...-----------------------------------From Padraig:In answer to your question, the energy dissipation from the detector isminimal - 300uW based on a 30V bias with upto say 10uA current draw.This scales with number of detectors.For the electronicsAt room temp 6-7mA of current draw at 5V gives about 60mWCooled this goes up by an order of magnitude.--------------------------------------Dr. Zisis Papandreou | email: zisis@uregina.caDepartment of Physics | tel. : (306) 585-5379University of Regina | tel. : (306) 585-4149Regina, SK S4S 0A2 | fax. : (306) 585-5659World Wide Web: http://www.phys.uregina.ca/sparro/zisis/