1. LumiReview280103.ppt P. Denes p. 1 Luminosity Monitor Review Concept Instrument TAN (TAS), count n Requirements Implications of the requirements on the design of the luminosity monitor New Mechanics Updated design for inert gas ionization chamber Suggestions/Compatibility with solid state detector Electronics Previous test beam results and current test beam needs Bill Turner, who would normally be presenting much of this, can not be here today, so we are filling in (at times perhaps imperfectly)

2. LumiReview280103.ppt P. Denes p. 2 Luminosity Monitor Concept D1tripletTAS tripletD1 TAN IP 140 m n LL RR Luminosity  N MIP from n shower Crossing Angle   L +  R Instrument TAN Massimo

3. LumiReview280103.ppt P. Denes p. 3 TAN IP Instrument a Copper Bar

4. LumiReview280103.ppt P. Denes p. 4 TAN Instrumentation Slot

5. LumiReview280103.ppt P. Denes p. 5 Detector Constraints - I. Charged particles swept away (Gas) Detector placed after several INT (few  ) m ~1 n per 3 pp interactions (in the acceptance) Offset due to ±150 µrad crossing angle Horizontal, vertical or 45° crossing ~ 80 x 80 mm 2 for detector Segment (for position) LHC Project Document No. LHC-B-ES-0004 rev 2.0

6. LumiReview280103.ppt P. Denes p. 6 Detector Constraints - II. Signal collection time < 25 ns Modest S/N performance: Shower fluctuations  ( N MIP )/ N MIP ~ 30%  1   P = 1% needs N ~3000 pp interactions Desired precision Number of events n / pp interaction

7. LumiReview280103.ppt P. Denes p. 7 Detector Constraints - III. Given large hadronic shower fluctuations, SNR ~ 4 or 5 is sufficient Effect of SNR on N to achieve P

8. LumiReview280103.ppt P. Denes p. 8 Requirements Update

9. LumiReview280103.ppt P. Denes p. 9 Requirements Total L Absolute L from experiments  L / L ~ 1% Reproducibility ~ 1% Integration time ~ 1s Bunch-by-bunch (most stringent: )  L / L ~ 1% Integration time ~ minutes And bringing beams into collision

10. LumiReview280103.ppt P. Denes p. 10 Total Luminosity m=0.33  INEL =80 mb SNR=5

11. LumiReview280103.ppt P. Denes p. 11 Bunch-by-bunch Luminosity m=0.33  INEL =80 mb SNR=5 2808 bunches

12. LumiReview280103.ppt P. Denes p. 12 Luminosity Optimization Transverse view at IP Beam 1 ** D beam-beam separation Beam 2  d for ,d <<  * D = d +  know d, measure  to get  to 0.1  *   L / L  0.5%

13. LumiReview280103.ppt P. Denes p. 13 Current Design Options Ionization Chamber GasSolid Active medium Radiation Hardness Mechanical stability Speed Noise (SNR) Ar + N medium replaceable fixed components  low mobility  doable CdTe  hardness to be shown  depends on contacting higher mobility trivial Very high TID - up to ~250 000 MRad/10 yrs Access as infrequently as possible

14. LumiReview280103.ppt P. Denes p. 14 Argon Ionization Chamber I0I0   = x GAP /v D charge/hadron = Q 0 x x GAP x P [Atm] x N GAP I 0 = 2 Q 0 v D PN GAP = 9.7 e – /MIP/mm x 231 MIP/h x x GAP x P x N GAP = 0.72 nA x v D [µm/ns] x P [Atm] x N GAP V+ x GAP N GAP =2

15. LumiReview280103.ppt P. Denes p. 15 Electronics Very high radiation levels  50  Cable between detector and preamp CDCD Z 0 (50  ) (Virtual) 50  If sufficient signal, 50  resistor can be real, otherwise 50  resistor has to be “virtual”

16. LumiReview280103.ppt P. Denes p. 16 Modified Ionization Chamber Design Area constrained: 4 quadrants A ~ 4x4 cm 2 Capacitance per gap C GAP =  A/x GAP Gap dimensions Gap topology Number of gaps Gas properties Update of previous mechanical design Goal: simplified construction  higher reliability Consider all configurations which fit into Cu bar volume Consider different gases / mixtures (simulation)

17. LumiReview280103.ppt P. Denes p. 17 Optimizing the layout Coax cable N GAP x GAP “50  ” Ionization Current I0I0 T Time Constant 50  x C DETECTOR

18. LumiReview280103.ppt P. Denes p. 18 Previous Approach I. Series-Parallel connection x GAP VV3V3V5V5V 2V2V4V4V

19. LumiReview280103.ppt P. Denes p. 19 Previous Approach II. N GAP = N SER x N PAR Effective gas volume = x GAP x N PAR C DETECTOR = C GAP x N PAR / N SER  Parasitics - Hard to achieve C DETECTOR, complex mechanics N GAP = 60 x GAP = 0.5mm N PAR = 10, L = 5mm N SER = 6

20. LumiReview280103.ppt P. Denes p. 20 Improved Speed Possible Previous Operating Point simulated with MAGBOLTZ

21. LumiReview280103.ppt P. Denes p. 21 Drift Velocity 050010001500 0 1 2 3 4 Velocity(cm/microsec) E(V/cm-atm) Ar+1%N2 Ar+1.5%N2 Ar+2%N2 Ar+3%N2 Simulation Measured Data vs. Simulation Ar (98%) N2 (2%) Ar (97%) N2 (3%) Ar (96%) N2 (4%)

22. LumiReview280103.ppt P. Denes p. 22 Example: Constant 6 mm Gas Volume Current Waveform into Preamplifier Current [µA] at 1 Atm Ar/N 2 (96::4)

23. LumiReview280103.ppt P. Denes p. 23 6x1 mm Gaps N has to be even Effective gas length Intrinsic capacitance Drift velocity L x v/C 5 mm 6 mm  (10/6) / 0.5  6/1 3.2 cm/µs 4.5 cm/µs  1::1 Previous version This version

24. LumiReview280103.ppt P. Denes p. 24 Detector Concept One ground “comb” milled from a solid Cu block Four signal “combs” Ceramic insulation/alignment pieces (machineable MACOR) Detector mechanical design: T. Loew, D. Cheng Vessel mechanical design: M. Hoff Fabrication design: N. Salmon, A. Mei

25. LumiReview280103.ppt P. Denes p. 25 Assembly I. Signal comb Alignment features (explained below)

26. LumiReview280103.ppt P. Denes p. 26 Assembly II. Ground planes 2 mm Cu / 1 mm gap (i.e. 4 mm between plates) 40 mm depth  < 10::1 aspect ratio - OK for machining Solid ground separates all 4 quadrants

27. LumiReview280103.ppt P. Denes p. 27 Assembly III. Alignment features

28. LumiReview280103.ppt P. Denes p. 28 Assembly IV. One ceramic face is metallized for bias filter and connections to rad- hard coax cable

29. LumiReview280103.ppt P. Denes p. 29 Available Space 96 mm 67 mm

30. LumiReview280103.ppt P. Denes p. 30 Quadrant Dimensions Not to scale 94 Ceramic Stainless Steel 38 40 Copper 0.5 2.5 3.54.0

31. LumiReview280103.ppt P. Denes p. 31 Absorber Bar

32. LumiReview280103.ppt P. Denes p. 32 Detector Housing (TAN Insert) Detector area Services to detector Direct connect or patch panel Compatible with any detector

33. LumiReview280103.ppt P. Denes p. 33 Detector Housing Signal+HV Connectors Gas Metal pressure seal Detector Volume Detector Volume Gas

34. LumiReview280103.ppt P. Denes p. 34 Constraints - I. Thin wall dimension designed so that vessel withstands 15 Atm.

35. LumiReview280103.ppt P. Denes p. 35 Constraints - II. Double-insulated, high-pressure SMA feedthroughs Rad-hard (SiO 2 ) cable 0.141 inch (3.6 mm) ø semi-rigid

36. LumiReview280103.ppt P. Denes p. 36 Complete Insert Insulated from TAN by 0.5 mm ceramic Rad-hard semi-rigid coax insulated by ceramic beads from housing Compatible with standard lifting mechanism

37. LumiReview280103.ppt P. Denes p. 37 Detector Mounted in Vessel

38. LumiReview280103.ppt P. Denes p. 38 Integration

39. LumiReview280103.ppt P. Denes p. 39 Engineering Solution in Preparation

40. LumiReview280103.ppt P. Denes p. 40 CdTe

41. LumiReview280103.ppt P. Denes p. 41 Alternate CdTe Layout Reconstruction with 10-disk geometry is complicated Could be simplified by constructing quadrant detector using 2-2.5 x 2-2.5 cm 2 CdTe (several sources) 3 x 3 array of 2-2.5 x 2-2.5 cm 2 CdTe 250 µ between chips

42. LumiReview280103.ppt P. Denes p. 42 CdTe Assembly Using Spring Contacts

43. LumiReview280103.ppt P. Denes p. 43 Detector Housing (TAN Insert) Same idea, but more cables (and no gas lines)

44. LumiReview280103.ppt P. Denes p. 44 Assembly

45. LumiReview280103.ppt P. Denes p. 45 Current Pulse from 2 x 2 cm 2 CdTe into 50 , 93 pF 7 ke - /MIP, 280 MIP

46. LumiReview280103.ppt P. Denes p. 46 CdTe vs. Ar+N 2  CdTe - radiation-induced leakage current  CdTe - Leakage current ~ T 2 e T  CdTe - complicated reconstruction - can be solved with different mechanics CdTe - Faster than Ar+N 2, deconvolution required Ar+N 2 - Active medium “easy to replace”  Ar+N 2 - Signal smaller than CdTe (less important - have to average over many pulses due to shower fluctuations) Franco

47. LumiReview280103.ppt P. Denes p. 47 Simulation 50% of signal per quadrant 6x1 mm gaps 6 ATM Ar (96%) N2 (4%) 4 cm/µs drift velocity  I 0 = 1 µA I0I0

48. LumiReview280103.ppt P. Denes p. 48 Pulse Speed A return to baseline within 25 ns is not necessary if Noise is uncorrelated Averaging over many samples is required in order to smooth out shower fluctuations The pulse shape is linear over the dynamic range Not only linearity at the peak, but also invariance of the shape with amplitude are required In this case, deconvolution is straight-forward

49. LumiReview280103.ppt P. Denes p. 49 Pulse for 1 pp Interaction

50. LumiReview280103.ppt P. Denes p. 50 Deconvolution - I.

51. LumiReview280103.ppt P. Denes p. 51 Deconvolution - II. A 1% error (linearity, mis-termination,...) results in a 20% error on a 1 interaction pulse preceded by a 20 interaction pulse

52. LumiReview280103.ppt P. Denes p. 52 Pulse Shape Uniformity A variation of pulse shape would mean that a 1 /a 0 is not constant Perfectly Linear

53. LumiReview280103.ppt P. Denes p. 53 Example - 5% Shape Non-Uniformity a 1 /a 0 differs by 5% in the 2 curves

54. LumiReview280103.ppt P. Denes p. 54 5% Shape Non-Uniformity Small effect since a 0 is constant. (Similar to saying pulse shape is non-linear, but gain at peak is calibrated)

55. LumiReview280103.ppt P. Denes p. 55 Timing Error Time window for 1% variation = 2 ns

56. LumiReview280103.ppt P. Denes p. 56 DAQ FEADCFPGA Delay LHC 40 MHz

57. LumiReview280103.ppt P. Denes p. 57 Timing Error For a single voltage sample per bunch, some timing error is tolerable. Timing error will, however, influence the de- convolution. Worst case: a pulse preceded by a train of pulses M times bigger. Then, the error on the small pulse is Massimo Alex

58. LumiReview280103.ppt P. Denes p. 58 Conclusions Gas detector: Much work has been done - 2 test beam campaigns(‘00, ‘01) New mechanical design  long-term reliability Ready for engineering prototype of final design 2 technologies (gas, CdTe) - both have promising features, both still need some R&D Plan: May ‘03: 25 ns SPS test beam (gas+CdTe) hadron irradiation of both designs