1. Update on the HBD Craig Woody BNL DC Meeting May 11, 2005

2. C.Woody, DC Meeting, 5/11/052 Status Summary  Construction of full scale prototype completed at the Weizmann and is currently being tested  Final detector design is under way at the Weizmann  Design of new GEM foils complete  Some final gas system parts are being ordered  Stainless steel gas lines in 1008 will be installed before or during next shutdown  Preamp order has been placed Currently on hold pending a review of possible ways to reduce radiation length budget  Design of digital electronics is under way at Nevis  Completed first trial test of small HBD prototype at LEGS

3. C.Woody, DC Meeting, 5/11/053 Full Scale Prototype at Weizmann

4. C.Woody, DC Meeting, 5/11/054 Full Scale Prototype Gas Tightness Test We started Nitrogen flow (200 l/h) with a single 50 um mylar window With single mylar we reached 15-20 ppm water level With double mylar window we reached 5-6 ppm Bypassing the HBD showed 2 ppm in the gas system On 19.04.05 we replaced 50 um window by 127 um mylar window coated with Al With this single window we reached the same 5-6 ppm On 06.05.05 we opened box and put into it several GEMs and resumed the Nitrogen flow I.Ravinovich

5. C.Woody, DC Meeting, 5/11/055 Final HBD Design Same design as full-scale prototype but: larger acceptance |  | ≤0.36  |  | ≤0.45  =110 o   =135 o smaller pad size a =16.7  15.6 mm Number of channels 1368  2304 Number of detector modules 16  24 GEM size 26 x 24  23 x 27 cm 2

6. C.Woody, DC Meeting, 5/11/056 New GEM Foil Design In the new GEM design the HV segmentation is done only on the top side of the GEM. There are 28 segments, 26x8 mm and 2x6.5 mm. The dimension on Z allows us to reach acceptance  =+/-0.44. We will ask CERN workshop first pilot production of the order of 10 GEMs, test them and then give them greenlight for the mass production. I.Ravinovich

7. C.Woody, DC Meeting, 5/11/057 HBD in the Retracted Position

8. C.Woody, DC Meeting, 5/11/058 Radiation Length Budget Preamps: 0.95 % Sockets: 0.60% Total = 0.92 + 0.54 + 0.95 +0.60 = 3.01 % CDR

9. C.Woody, DC Meeting, 5/11/059 First Test of Small HBD Prototype at LEGS The beam was studied extensively, so that the apparatus could be precisely aligned. Trigger = H1+S1+S2 Veto Cut Applied Off-line B.Azmoun LEGS e - Tagger Cave 64 Ch. e - Hodoscope S1 S2 Veto Tagged ~2 GeV e - Beam H1 ~50cm CF 4 Radiator CsI 3-GEM 3x3 pad array (~1.5”x1.5” ea.) Retractable VUV Lamp Retractable Fe-55 SS Vessel LEGS Cherenkov Counter w/ ~2” Lucite

10. C.Woody, DC Meeting, 5/11/0510 Gas Quality Before and After Test Water “peaks” There were no means to test the gas quality during the test, however we did test the gas quality before and after the test, under more or less the same conditions (i.e., similar purging period and flow rates). B.Azmoun

11. C.Woody, DC Meeting, 5/11/0511 CsI Photocathode Photocathode (produced at Stony Brook) was stored in a sealed vessel filled with N2 (but possibly not the best environment) for two weeks prior to the test, and may have suffered some additional deterioration during its installation into the detector (we have no glove box !!). The last time the GEM PC was measured, its integrated QE was ~ half that of the nominal value. B.Azmoun

12. C.Woody, DC Meeting, 5/11/0512 Positive Bias Results Expected primary charge from dE/dx: dE/dx MIP = 7keV/cm * 2.44mm / (54eV/e - -ion pair) = 31.6 e - ’s For ~1GeV e - ’s  Relativistic Rise factor: 31.6*1.4 = 44 e - ’s Measured primary Charge from dE/dx: At Gain of ~6500, Landau Mean ~ 45e-’s This result is derived from a “Quick Analysis”,where the Landau mean was roughly approximated…a more rigorous analysis will be done shortly E D = + 1.2 kV/cmB.Azmoun

13. C.Woody, DC Meeting, 5/11/0513 Negative Bias Results = 2.0 = 1.8 = 1.0 = 1.4 = 6.9 = 0.9 = 0.8 = 0.7 Note: The data presented in the histograms above is not the data set that was analyzed, and is meant to give an overall qualitative idea of the data, rather than act as an exact reference. E D = - 0.3 kV/cm B.Azmoun Mean number of Cherenkov pe-’s measured: Instead of adding pulse heights event by event for all the pads, a rough approximation of the mean number of total photoelectrons is calculated by summing the mean pulse height for each pad…a more rigorous analysis will be done shortly. The SUM of the avg. number of pe - ’s contributed from each pad = 16.25pe - ’s (Gain=6500) Correcting for known Detector Inefficiency’s 1.6% loss of primary pe-’s due to absorption in gas 2.Integrated QE is low by a factor of 2.11 3.pe Collection Efficiency ~90% Corrected # of pe-’s = 16.25 * 1.06 * 2.11 * (1/0.9) = 40 pe ! (Remember, this is a rough approx.) The final measurement shows a lot of promise!

14. C.Woody, DC Meeting, 5/11/0514 Schedule  Ship full scale prototype to BNL some time this summer for testing of electronics and readout chain Preamps are presently available, but prototype of digital readout will not be ready until later this the year  Begin construction of final detector at Weizmann this summer  Install main components of gas system during next shutdown Will likely not have recirculation capability (cost of CF 4 ~ $600/bottle)  Begin GEM production at CERN over the summer  Explore CsI production capability at JLAB  Need to begin constructing assembly facility at Stony Brook Goal is to have the detector ready for an initial test sometime during Run 6