From settles@mppmu.mpg.de Mon Dec 1 15:47:55 2008 Date: Mon, 1 Dec 2008 11:31:41 +0100 (CET) From: Ronald Dean Settles To: lctpc@desy.de Subject: Advanced endcap: summary mtgs 10-15Nov2008, plans for 2009 Dear lctpc friends, We have had five meetings up to now, 3 last year, then the 2 this year were: #4 on 10.11.1008, see http://ilcagenda.linearcollider.org/conferenceDisplay.py?confId=3123. and #5 on 15.11.2008, see http://ilcagenda.cern.ch/conferenceDisplay.py?confId=3140. A summary of #5 is appended (below the line of ****) to that of #4 which has a few corrections, so that you have all of the info at your disposal in one place. Here is the updated planning up to the ILD LOI. 2007: --Three meetings #1 14June, #2 26July, #3 10Oct 2008: --#4 at CERN, on 10 Nov 2008: summary see below --#5 at LCWS2008, on 15Nov 2008: summary see below 2009: --#6 at CERN, on ??Jan 2009 (day,place,time to be announced). --#7 at ILD Korea (16-18 Feb 2009), advanced endcap on 15 Feb or during the ILD meeting --#8 at TIPP09, on 11 March 2009 (place,time to be announced} Comments are welcome... Greetings, Ron -------------------------------------------------- Advanced-Endcap#4 10/11/2008 http://ilcagenda.linearcollider.org/conferenceDisplay.py?confId=3123 Agenda: ------- 1. TPC-endcap issues (15') Introduction by Ron Settles 2. LCTPC electronics issues (15') by Luciano Musa 3. Cooling issues from CMS experience (15') by Alain Herve 4. DAQ issues (15') by Xavier Janssen -------------------------------------------------- Summary: -------- 1. TPC-endcap issues. - We had three advanced-endcap meetings last year: 14 June, 26 July 2007 and 10 October 2007. The first two covered mainly the new electronics and the third included first thoughts by Luciano on the layout of and heat generated by the "advanced-endcap" electronics. - There are three main, highly-correlated and sometimes self-contradicting aspects: electronics (as many pads as possible), cooling (as little heat generated as possible) and mechanics (as thin as possible). In addition there are two main developments: standard TPC or pixel TPC. - The density we choose will be governed by cooling (heat) and mechanics (X_0), as well as by the momentum resolution we want. How the problem was solved by Aleph was shown: 25% X_0 for 22000 pads and 1.3kW per side cooled using combined water and forced-air cooling. - The heat generated will depend not only on the electronic density but also on how well the power-switching works. If it turns out we are generating too much heat or the endcap is too thick due to electonic density, we will have to reduce the number of pads and there are ideas as to how to do this while maintaining the momentum resolution, but the price you pay is higher occupancy. =>=> However we don't want to consider this option yet, because we are still in the process of understanding the issues. 2. LCTPC electronics issues. Luciano reviewed the Alice endcap: 285000 pads per side, an order of magnitude more that Aleph. Whereas Aleph only had the preamps on the endcap, Alice has the whole PASA/Altro chain which sums up to 11kw per side to be cooled. Copper cladding of all the electronics and water cooling solved the Alice heat problem, but Alice does not worry about thickness of the endcap so that such a solution for the LCTPC is not possible. The strategy for LCTPC is that power pulsing will work and reduce the heat to a managable level. Luciano found that a density of 330000 pads per m^2 would be possible, based on preliminary layout of the PCB. He also showed first thoughts towards a power-pulsing circuit; if 1:100 power reduction can be achieved, that would leave 167 W/m^2 x 1/3.3 = 50 W/m^2 to cool for 1 million pads per endcap. Finally he said that a cooling layer can be included in the PCB. 3. Cooling issues from CMS experience. Alain reviewed the ideas used for CMS; these ideas are meant to open the discussion for the lctpc: - Each sub-detector is basically adiabatic wrt others. - The bulk of heat is removed locally by water as near as possible of where heat is created. Water is still the best liquid for that; there exist alternatives to water but they are expensive. - The remaining part of heat is removed by natural convection in the surrounding inert atmosphere; vacuum vessel and massive detector components are used as cold sinks. This is compatible with an inert atmosphere inside the vacuum vessel as required for fire protection. - Alain expressed concern that power-pulsing may cause problems for the mechnical stability of the detectors. 4. DAQ issues. Xavier dispayed first thoughts. - The advanced endplate electronics will be much more highly integrated than now and include more FEC and RCU functionalities. What is put on the endcap and what goes into the electronic hut must be decided. -For the several options (eg AFTER,ALTRO,TOT) for the advanced-endplate electronics, a common data transfer protocol and DAQ should be defined. -A "trigger" concept will be needed. E.g., the "trigger" should wake up the electronics before the bunch-train arrival and prepare for arrival of the data, and then put the electronics back to sleep after the bunch train has passed. -Also data transfer needs redundancy and Xavier showed the architecture being planned by CALICE. ***************************************************************** Agenda Advanced-Endcap#5 15/11/2008: http://ilcagenda.cern.ch/conferenceDisplay.py?confId=3140. ------- 5. Summary of meeting#4 (15') by Ron Settles 6. Ideas for pixel endplate (15') by Jan Timmermans 7. Ideas for standard-electronics endplate (15') by Dan Peterson -------------------------------------------------------------- 5. Summary of meeting#4 See above the line of *****. 6. Ideas for pixel endplate. Jan reviewed the status of the pixel work which is progressing mainly with the two MPGD amplifications, micromegas and gem. After showing that pixel chip medipix could record tracks in first attempts, timed readout (timepix) was then developed, as was a discharge protection layer. An integrated production of pixelchip, discharge protection and MSGC has been successfully demonstrated. Alternatve gem grids (running in a mode similar to micromegas), double micromegas layers (twingrid), as well as configurations with more integration seen on Jan's slides6-8 are being attempted. The cooling (slide9) of 30W/m^2 would be easy to solve if a factor of 100 can be gained from the power pulsing. First ideas for the layout from Harry van der Graaf are shown on slides10-12. It is clear that the cooling strategy whould best be the same for all ILD subdetectors (see point 3. above) for reasons of simplicity (not to make the same mistake as some LHC detectors). 7. Ideas for standard-electronics endplate. Dan presented three options for the next endplate-prototype to follow the present one being commissioned at the LP: (1) one using the current "LP1"-endcap-layout, (2) an "LP2" endcap with lighter matierial, (3) a new endplate with material/panel-layout as prototype for the LCTPC. He listed several scenarios: -thinning the aluminum (1), -all beryllium (1,2) why not (3)?, -composites (2?,3) why not (1)?, -hybrid of composites with metal (1,2,3). -space-frame construction (2,3). The present LP endplate fully loaded with panels will have ~30%X_0, and Dan showed some way of thinning it (slides2-4) if option (1) is chosen. He showed practical applications being used in satellite experments ("space-frame constructions"), where weight and cooling requirements are very stringent. (Note that the Hubble mirror on slide5 should have a diameter of ~2.3m, making the JWST mirror next to it about 25% bigger than the LPTPC endcap). Several pictures of high-tech satellite examples of light, strong constructions followed. We of LCTPC will have to agree as to which of Dan's options above would be the best next step.