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Diamond Manufacturers for ATLAS Upgrades March 26, 20121R. Kass Brief Overview: Next Upgrade (IBL): Diamond Beam Monitor (DBM) News from two diamond manufacturers.

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Presentation on theme: "Diamond Manufacturers for ATLAS Upgrades March 26, 20121R. Kass Brief Overview: Next Upgrade (IBL): Diamond Beam Monitor (DBM) News from two diamond manufacturers."— Presentation transcript:

1 Diamond Manufacturers for ATLAS Upgrades March 26, 20121R. Kass Brief Overview: Next Upgrade (IBL): Diamond Beam Monitor (DBM) News from two diamond manufacturers E6/DDL II-VI News from diamond cutting & thinning companies Summary

2 March 26, 2012 Diamond Beam Monitor 2 BCM DBM: 3.2<η<3.5 R. Kass Part of IBL upgrade – Bunch-by-bunch luminosity monitor (aim < 1 % per BC per LB) Finer segmentation & larger acceptance than BCM Never saturates Internal stability monitoring – Bunch-by-bunch beam spot monitor Need triple-module telescopes for (limited) tracking Can distinguish hits from beam halo tracks Unbiased sample, acceptance extends far along beam axis – Baseline: 4 telescopes of 3 IBL modules per side → 24 total diamonds – Avoid IBL insertion volume and ID acceptance (η>2.5) – Place in pixel support structure close to detector and beam pipe

3 DBM Diamond Sensor Plan Two diamond suppliers involved: DDL/E6 (UK based) II-VI (US based) March 26, 2012R. Kass3 Diamond Sensors for DBM: type: polycrystalline CVD diamond size: 21 x 18 mm 2, 525 ± 25  m thickness number: need for DBM modules 24 + spares 5 for Irradiation studies 21 x 18 mm 2 pCVD diamond Some parts already in hand that need cutting and/or thinning

4 Sensors from DDL Ten Detectors ordered from DDL/E6 (thick E6 wafer – Wafer 9) – Plan was for wafer to be tested at OSU → wafer characterization → device selection – Wafer 9 received from E6 11-Jan-2012 Rind still attached Defect level looks ok – Wafer 9 returned to E6 - rind removal – Wafer arrived at OSU, test grid applied, being testing March 26, 2012R. Kass4

5 Wafer 9 from DDL March 26, 2012R. Kass Growth side Substrate side 5 5 inches

6 Thickness of wafer 9 from DDL March 26, 2012R. Kass6 As grown thickness varies from ~1.24 to 1.48 mm

7 Collection Distance & Current Characterisation of DDL’s wafer 9 March 26, 2012R. Kass7 We are almost finished measuring the CCD & I in all regions of the wafer Expect to finish measuring the CCD & ship back to DDL/E6 mid-week Good regions have I <5 nA at 1000V in air All regions of wafer 9 look good CCD (  m)current (nA)

8 Electric Field Characterisation of DDL’s wafer 9 March 26, 2012R. Kass8 Need to take into account the varying thickness of the wafer Scale previous CCD plot to E=0.66V/  m This information allows us to make a “cut map”

9 Cut Map Example March 26, 2012R. Kass9 Based on the CCD and thickness info we divide the wafer into “sensors” wafer 8 Wafer 8 was cut into eleven 2 x 2 cm 2 sensors

10 E6/DDL Production Capabilities Get FE-I4 sensors per wafer Ordered 10 DBM Sensors detectors from DDL’s wafer 9 21 x 18 mm 2 with CCD>200  m at 1000V Each piece will be thinned to 525  m Expect the pieces to arrive in June Processing takes 6-10 weeks after return of wafer Expect to have access to wafers/year determined by the orders we place March 26, 2012R. Kass10

11 Work with II-VI Can grow thick wafers - 2 mm thick – grown for another application Very good CCD results – V/µm Problems with N 2 and growth rate problems showed up at the edges 11 Wafer Results 5 inches II-VI makes “optical grade” cvd diamond laser windows.. II-VI is the “2 nd Company” March 26, 2012R. Kass

12 Sensors from II-VI March 26, 2012R. Kass12 Proceeding to develop additional supplier of detector grade material based on their samples Good CCD results – V/µm even though grown for another application and problems with N 2 – Modified growth process ATLAS committed to produce one detector grade wafer by June with option for second wafer Quote received 9-Feb: specified ccd >250 thickness ATLAS placed order for 10 parts with option for 10 more

13 Cutting & Thinning Parts in Hand Have tested part thinning (750μm → 525μm) – 1cm x 1cm part used, came back fine Sent first 2cm x 2cm parts for thinning returned with edge problems we are looking into a laser trimming repair looks do-able Sent: one 2x6 for cutting & thinning four 2x2’s for thinning Expect three weeks to get 2x2 parts back If ok → send remainder of parts March 26, 2012R. Kass13

14 Summary March 26, 2012R. Kass14 Two manufacturers are in place: DDL, II-VI Three orders of sensors from two manufacturers: DDL: 11 (wafer 8) + 10 (wafer 9) wafer 9 being tested II-VI 10 (with an option of another 10) looking forward to receiving their pieces in May CCD measurements on DDL’s wafer 9 just about finished will ship back to DDL/E6 shortly Progress on wafer thinning working with 2 companies in the US Can now get 100’s of sensors/yr

15 Extra Slides March 26, 2012R. Kass15

16 16 Introduction: Diamond as sensor material PropertyDiamondSilicon Band gap [eV] Low leakage Breakdown field [V/cm]10 7 3x10 5 Intrinsic R.T. [Ω cm]> x10 5 Intrinsic carrier density [cm -3 ]< x10 10 Electron mobility [cm 2 /Vs] Hole mobility [cm 2 /Vs] Saturation velocity [cm/s]0.9(e)-1.4(h)x x 10 7 Density [g/cm 3 ] Atomic number - Z614 Dielectric constant – ε Low cap Displacement energy [eV/atom] Rad hard Thermal conductivity [W/m.K] Heat spreader ~ Energy to create e-h pair [eV] Radiation length [cm] Interaction length [cm] Spec. Ionization Loss [MeV/cm] Aver. Signal Created / 100 μm [e 0 ] Low Noise, Low signal Aver. Signal Created / 0.1 X 0 [e 0 ] Single-crystal CVD & poly CVD fall along the same damage curve Proton damage well understood At all energies diamond is >3x more radiation tolerant than silicon Radiation Studies

17 17 Radiation Damage - Basics  Charge trapping the only relevant radiation damage effect  NIEL scaling questionable a priori GE gap in diamond 5 times larger than in Si  Many processes freeze out  Typical emission times order of months  Like Si at 300/5 = 60 K – Boltzmann factor A rich source of effects and (experimental) surprises ! Radiation induced effect Diamond Operational consequence Silicon Operational consequence Leakage current small & decreases none I/V = αΦ α ~ 4x A/cm Heating Thermal runaway Space charge~ nonenone ΔN eff ≈ -βΦ β ~ cm -1 Increase of full depletion voltage Charge trappingYes Charge loss Polarization 1/τ eff = βΦ β ~ 5-7x cm 2 /ns Charge loss Polarization 17OSU, Nov 9, 2011 R. Kass: DOE Review


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