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Radiation Backgrounds In and Near the HGTD: HGTD Studies Following General Meeting, July 7, 2016

Radiation Backgrounds In and Near the HGTD: HGTD Studies Following General Meeting, July 7, 2016. Erich Varnes and Michael Shupe, Univ. of Arizona. Topics Presented by AZ on July 7: * Phase 2 rates and doses in the ATLAS baseline inner detector, and the effects of EC moderator.

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Radiation Backgrounds In and Near the HGTD: HGTD Studies Following General Meeting, July 7, 2016

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  1. Radiation Backgrounds In and Near the HGTD:HGTD Studies Following General Meeting, July 7, 2016 Erich Varnes and Michael Shupe, Univ. of Arizona Topics Presented by AZ on July 7: * Phase 2 rates and doses in the ATLAS baseline inner detector, and the effects of EC moderator. * Phase 2 rates and doses in the for various Arizona HGTD design options, and effects in the inner detector. Additional Studies up to July 17: * This report describes five additional HGTD options. The first three options were recommended by the HGTD group, to match options being simulated by others. The fourth option has two W plates instead of three (arising from a question at the July 7th meeting.) Thefifth option is based on the third option, and adds 5 cm of BPE to the front of the outer section.

  2. The next few slides are a review of earlier studies of the ATLAS baseline geometry with and without borated polyethlene (BPE) on the front of the endcap calorimeter, with the focus on rates and doses in the inner detector.In this report, the inner detector geometry is the I.D. for Run 1. The endcap BPE study, and the HGTD studies, will be redone when the ITk geometry is available, along with the final VI beampipe.

  3. NIEL Dose [1 MeV equiv N/cm^2/3000/fb]: The effect of 5cm Bpoly on the EC ATLAS Baseline EC Bpoly removed EC Bpoly 5cm ID ID FCal FCal If the EC Bpoly is removed, the NIEL dose in the inner detector increases by a factor of ~2 in the tracker regions near the face of the endcap calorimeter.

  4. NIEL Dose with 3000/fb near end of ID: Z=344-348cm R=5-70 cm All Options – EC Bpoly, HGTD, etc. No BPE on endcap calorimeter Baseline ATLAS with 5cm of BPE on the endcap This is the ratio for with EC BPE removed. It shows the increase by the factor of 2 in the ID at large |Z|.

  5. Hadrons>20 MeV/cm^2/3000/fb - Displacement Damage ATLAS 2013 ATLAS Baseline EC Bpoly removed ID ID FCal FCal Characteristic of high-energy backgrounds, the doses of hadrons >20MeV do not change significantly with the presence/absence of BPE on the endcap cryostat.

  6. SEU Rates: Ppi>10MeV + N>2MeV [/cm^2/3000/fb] ATLAS 2013 ATLAS Baseline EC Bpoly removed ID ID FCal FCal A mixed flux with different energy thresholds: SEU rates. The inner detector rates increase slightly near the front of the EC when the BPE is removed.

  7. Thermal Neutrons [kHz/cm^2]: Possible increases in flux of capture gammas Baseline with Bpoly ATLAS Baseline EC Bpoly removed ID ID FCal FCal The thermal neutron rate in the inner detector increases significantly if the EC Bpoly is removed. If the ITk electronics contains Boron, neutron capture could create a large flux of capture gammas in the inner detector region (with or without Bpoly). Also, neutron moderation due to hydrogenic materials in the Run1 ID is evident.

  8. The following slides show rates and doses in the inner detector for the new HGTD options simulated since the HGTD meetings on July 6th and 7th. Emphasis is on NIEL dose changes in the inner detector and in the HGTD itself. Some additional backgrounds of interest are also shown for the inner detector and the new HGTD options. In all HGTD options, there is 5cm of BPE on theouter face of the endcap calorimeter (EC), starting at the outer radius of the HGTD (Ro = 60 cm)

  9. Geometries for five new HGTD Option Studies 5 HGTD Options Studied: 60-28 cm28-5 cm AIR AIR BPE BPE 3W BPE 2W+BPE BPE 3W+5cmBPE BPE HEC1 EC Warm Wall EMEC 5cm Bpoly on EC face 60 cm Air, BPE, or W in 3 gaps 28 cm FCal Air or BPE in 3 gaps 5 cm Alcove Moderator, as currently in ATLAS 9

  10. Plate Level Geometry for the HGTD Outer and Inner Regions This example shows the option with 3 W plates outer, and 3 BPE inner HGTD Plate-level Geometry 5cm BPE on EC W W W For the one option with 5 cm BPE on front Mountings B B B Bpoly Inner radius is 5 cm

  11. NIEL Dose Studies

  12. NIEL Dose [1 MeV equiv N/cm^2/3000/fb] HGTD Option Air-Air ATLAS Baseline All gaps Air: R=60-5 cm ID ID FCal FCal The NIEL dose in the inner detector increases in the ID at large |Z|. But the increase is smaller than in Slide 2, largely due to the 5 cm BPE on the EC beyond R=60cm.

  13. NIEL Dose [1 MeV equiv N/cm^2/3000/fb] HGTD Option BPE-BPE ATLAS Baseline All gaps BPE: R=60-5 cm ID ID FCal FCal In this HGTD option, the “3” gaps are filled with BPE instead of Air. The NIEL dose is somewhat smaller than in the previous slide due to moderation of neutrons by BPE.

  14. NIEL Dose [1 MeV equiv N/cm^2/3000/fb] HGTD Option 3W-3BPE ATLAS Baseline 3W R=60-28 cm, BPE R=28-5 cm ID ID FCal FCal This HGTD option has W in the outer section and BPE in the inner. The dose in the ID is similar to that in Slide 3. It is lessened by 5cm BPE for R>60cm, and increased by the added material, W, for 60cm > R > 28 cm.

  15. NIEL Dose [1 MeV equiv N/cm^2/3000/fb] HGTD Option 2W-BPE All Else ATLAS Baseline 2W: R=60-28 cm, All Other Gaps BPE ID ID FCal FCal This option is the same as that in the previous slide, but with the middle plate of W replaced by BPE. The rates are lowered slightly by the removal of 1X0 of W and the addition of BPE.

  16. NIEL Dose [1 MeV equiv N/cm^2/3000/fb] 3W(5cm BPE front)-3BPE ATLAS Baseline Prev 3W-3BPE with 5cm BPE on front of 3W section ID ID FCal FCal This option also begins with that of 2 slides ago. But here the difference is that 5 cm of BPE has been put on the front of the W section. The added BPE lowers the inner detector NIEL dose almost to ATLAS baseline levels (no HGTD).

  17. NIEL Dose near end of ID: Z=336-340cm R=5-70 cm Here are the NIEL doses and ratios vs R in a dZ band near the end of the ID for the five HGTD options and the no-HGTD baseline. Baseline Air-Air BPE-BPE 3W-3BPE 2W-Else BPE 5cm BPE on W

  18. NIEL Dose inside HGTD: Z=348-352cm R=5-70 cm Here are the NIEL doses and ratios vs R in a dZ band inside the HGTD for the five HGTD options and the no-HGTD baseline. Baseline Air-Air BPE-BPE 3W-3BPE 2W-Else BPE 5cm BPE on W

  19. Thermal Neutron Studies

  20. Thermal Neutrons [kHz/cm^2] HGTD Option Air-Air ATLAS Baseline All gaps Air: R=60-5 cm ID ID FCal FCal By comparing this to Slide 6, one can see that the Air-Air HGTD does less moderation of low energy neutrons (some H in G10) than having 5 cm of BPE on the full face of the EC

  21. Thermal Neutrons [kHz/cm^2] HGTD Option BPE-BPE ATLAS Baseline All gaps BPE: R=60-5 cm ID ID FCal FCal With all HGTD gaps filled with BPE, the green contour in front of the HGTD has reduced, so there is some additional neutron moderation going on.

  22. Thermal Neutrons [kHz/cm^2] HGTD Option 3W-BPE ATLAS Baseline 3W R=60-28 cm, BPE R=28-5 cm ID ID FCal FCal Similar to option on previous slide.

  23. Thermal Neutrons [kHz/cm^2] HGTD Option 2W-BPE All Else ATLAS Baseline 2W: R=60-28 cm, All Other Gaps BPE ID ID FCal FCal Similar to option on previous slide

  24. Thermal Neutrons [kHz/cm^2] HGTD Option 5cm BPE on 3W ATLAS Baseline Prev 3W-3BPE with 5cm BPE on front of 3W section ID ID FCal FCal Additional reduction due to more moderation (and neutron capture) in front of the absorber section.

  25. Thermal Neutrons near end of ID: Z=336-340cm R=5-70 cm Here are the thermal neutron rates and ratios vs R in a dZ band near the end of the ID for the five HGTD options and the no-HGTD baseline. (The fluctuations are due to simulation statistics.) Baseline Air-Air BPE-BPE 3W-BPE 2W-Else BPE 5cm BPE on W

  26. Thermal Neutrons inside HGTD: Z=348-352cm R=5-70 cm Here are the thermal neutron rates and ratios vs R in a dZ band inside the HGTD for the five HGTD options and the no-HGTD baseline. Differences are due to materials in the outer sections. Baseline Air-Air BPE-BPE 3W-3BPE 2W-Else BPE 5cm BPE on 3W

  27. Energy Deposition in the ID and HGTD:The flux plots for all 5 HGTD options (below) look very similar. But one variable feature is the energy deposition in the innermost module of the EMEC. The energy densities there can be seen to differ, depending on the amount of material in the outer section of the HGTD in front of that module.Due to the available pixelation in Z (4cm), the next five slides cannot be used for determining local rates in the individual plates of the HGTD.However, the R plot inside the HGTD (slide 34) can be used for a first approximation of energy deposition rates in the W plates since their mass fraction dominates the total material in the outer section of the HGTD within the Z range 348-352 cm.

  28. Energy Deposition [GeV/cm^3/s] HGTD Option Air-Air ATLAS Baseline All gaps Air: R=60-5 cm ID ID FCal FCal

  29. Energy Deposition [GeV/cm^3/s] HGTD Option BPE-BPE ATLAS Baseline All gaps BPE: R=60-5 cm ID ID FCal FCal

  30. Energy Deposition [GeV/cm^3/s] HGTD Option 3W-BPE ATLAS Baseline 3W R=60-28 cm, BPE R=28-5 cm ID ID FCal FCal

  31. Energy Deposition [GeV/cm^3/s] HGTD Option 2W-BPE All Else ATLAS Baseline 2W: R=60-28 cm, All Other Gaps BPE ID ID FCal FCal

  32. Energy Deposition [GeV/cm^3/s] HGTD Option 5cm BPE on 3W ATLAS Baseline Prev 3W-3BPE with 5cm BPE on front of 3W section ID ID FCal FCal

  33. Energy Deposition near end of ID: Z=336-340cm R=5-70 cm As expected, the rate of energy deposition in the air in front of the HGTD is small due to the low density of air. Baseline Air-Air BPE-BPE 3W-BPE 2W-Else BPE 5cm BPE on W

  34. Energy Deposition inside the HGTD: Z=348-352cm R=5-70 cm The rate of energy deposition in the HGTD is large, especially in the tungsten plates. This dZ range contains all W plates, which could be treated as the primary heat sources. Baseline Air-Air BPE-BPE 3W-3BPE 2W-Else BPE 5cm BPE on W

  35. Ionizing Dose:Like energy deposition, ionizing dose is localized within the massive (sometimes small) structures of detectors.We have not yet set up the scoring to use the individual volumes in the HGTD plate geometry to score rates and doses at plate level.For this reason, only one slide is included here.On our coarse scale, it shows that the ionizing dose in the innermost EMEC module shifts toward the HGTD when the HGTD has substantial mass (W plates).

  36. Ionizing Dose [Gy/3000/fb] – HGTD Option 3W-3BPE ATLAS Baseline HGTD 3W-3BPE ID ID FCal FCal The ionizing dose in the inner detector is little affected by the HGTD. But material in the preshower does move the ionization centroid forward at the inner EMEC.

  37. Future Studies of Rates and Doses from HGTD Options -> We hope soon to compare our new G3/Gcalor HGTD studies to those being done by other WG members. -> Our VI beam pipe geometry will need to be updated if the 3-segment scheme is adopted. -> Accurate studies of inner detector rates cannot go forward until the ITk design is finalized, and translated into simulation geometries. -> We plan to compare the rates and doses predicted by our simulations to the backgrounds limits for electronics and sensors, as those parameters are better known.

  38. The Slides Below Give Locations of All Results The Arizona group uses the Phojet event generator, Geant3, for detector description and particle transport, with GCalor for neutron transport. The G3/Gcalor interface was written by Christian Zeitnitz.

  39. Files Used For Studies Presented Here This talk contains only a small fraction of the information coming from these simulations. All studied rates and doses are available at the site below, in the subdirectories listed on the next slide. Location of files: http://atlas.physics.arizona.edu/~shupe/Cavern_Backgrounds_Phase2/ Select Study (list on next slide): then FLUXPLOTS or FLUXTEXTS Available doses and particle fluxes: Detector impact: energy deposition, NIEL dose, ionizing dose, hadrons > 20 MeV, SEU rates, star densities (for activation). Particles: total neutrons, neutrons > 100 keV, thermal neutrons, photons, electrons, protons, charged pions, muon single particle detector rates. 39

  40. Subdirectories Used for ATLAS Base and HGTD Studies Baseline ATLAS with New beampipe and NSW, and two options: Phase2_NBP_NSWA_Baseline_14TeV Phase2_NBP_NSWA_Baseline_NoECModr_14TeV HGTD Options: HGTD Air60to5 14TeV HGTD BPE60to5 14TeV HGTD W60to28 BPE28to5 HGTD 2W60to28 BPE60to5 HGTD WP Plus5cmBPEonW Air-Air BPE-BPE 3W-BPE 2W-Else BPE 5cm BPE on W 40

  41. Radiation Background Normalizations In AZ Phase 2 Studies As in past radiation background studies, the CM energy is 14 TeV. But we have changed the normalization of the flux and dose maps and histograms to match Phase 2 conditions. Up to 2015 studies used the luminosity 10^34 [cm^2/s]. But we now use the Phase 2 levelled luminosity of 5 X 10^34. This factor of 5 affects all rate calculations. In the past, doses were for one running year of 10^7 s, leading to an integrated luminosity of 100/fb. But now we are reporting doses for the full Phase 2 expectation of 3000/fb, increasing the doses by a factor of 30.

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