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Options for HF (Phase II Upgrade)

Options for HF (Phase II Upgrade). Aldo Penzo (INFN –Trieste). HF designed to be “intrinsically” radiation - hard ; Technical/financial compromises may limit some HF components’ lifetime (for instance up to ≈ 5 10 5 pb -1 )

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Options for HF (Phase II Upgrade)

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  1. Options for HF (Phase II Upgrade) Aldo Penzo (INFN –Trieste) • HF designed to be “intrinsically” radiation - hard; • Technical/financial compromises may limit some HF components’lifetime (for instance up to ≈5105 pb-1) • Activation of HF elements may prohibit manipulation for servicing, repair, etc. • HFcomplete replacement may be the only practical solution for SLHC… • In this case a variety of options for HF upgrade may be considered… Forward Calorimetry Working Group CMS Upgrade Workshop FNAL, 29 Oct 2009 1

  2. CMS Forward Region HF IP HF Absorber & Fibers 2

  3. Phase I - II Upgrades Two long shutdowns (1 year) (other shutdowns < 5 months): • 2014: new linac and new low-beta quads • ~2018: to be decided 2011-12, could be new PS/SPS • CMS upgrades implemented before/during 2014 shutdown are Phase I. • Expected luminosity before 2014 shutdown ~ 1.5 1034 • Upgrades implemented after 2014 shutdown are Phase II. • Expected luminosity by 2018 3 1034, eventual Phase II luminosity could be as high as 1 1035 Phase I Phase II 3

  4. Special HF components/properties • Čerenkov Calorimeter • ~250 tons iron absorber (8.8 lI) • ~ 1000 km quartz fibers (0.8mm diam) • Č light yield ≈ 0.1 ionization (scintillator) • mainly e± (T ≥ 0.2 MeV; b≥ n-1 ≈ 0.7) • Strongly non-compensating : e/h ≈ 5 (e/p ≈ 1.4) • Light yield ~ 0.3 phe/GeV • ~ 2000 PMT read-out • 36 wedges azimuthally; 18 rings radially • (Segmentation DhxDf = 0.175x0.175) • [dh~ 0.03, df~ 0.03 rad] • Uniformity (transverse) ± 10% 4

  5. HF summary radiation budget (Y. Onel, March 2009 CMS HCAL Upgrade Meeting) Fluence of hadrons (E>10 keV) in cm-2 s-1 (upper plot) Radiation dose in Gy (lower plot) in HF and its surroundings. (Values for 5 105 pb-1) 5

  6. Expected HF Fiber Exposure and Scenario • These numbers are without recovery of fibers. We expect the fiber to recover at least 20% at each shutdown. • QP Fibers cannot survive beyond 1 Grad. They’ll need to be replaced with QQ fibers after 10 years of LHC run (or equivalent dose). • The PMTs have sensitivity range nicely fitting with Fiber “sweet range” of 380nm-580nm. • PMT HV adjustment can easily make up for lost light intensity due to radiation. (Y. Onel, March 2009 CMS HCAL Upgrade Meeting) 6

  7. HF radiation budget at PMT • Recent radiation background simulations show improvement in the design of the shielding around the PMT region by a factor of ~two. There is no issue with the radiation dose or neutron flux where the PMTs are located. • All neutrons 2.54x1012 • Neutrons (E>100KeV) 1.63x1012 • Neutrons (E>20 MeV) 5.12x1011 • Ch. Hadrons 2.26x1010 • Muons 4.65x109 • Photons 1.53x1012 • Dose 7 krad For 10 years @ 1034 Luminosity: Activation of absorber ~10 mSv/h (60 days LHC run/1 day cool-down) Servicing HF will be hard…!!! 7

  8. Radiation on PMTs • Almost all studies agree that after 10 years the total radiation on PMTs will be less than 100 Gy = 10 kRad • This radiation primarily comes from neutrons. Charged hardons and muons will be around 1012 /cm2 for 10 year period. • When a PMT is exposed to radiation, the cathode sensitivity and secondary emission ratio exhibit very little variation. • The variation chiefly results from a loss of transmittance through the glass window due to coloring of the glass. • This plot is for 2mm glass thickness, it shows Hamamatsu tests with neutrons Conclusion: HF PMTs will NOT have any significant light loss due to radiation !! (Y. Onel, March 2009 CMS HCAL Upgrade Meeting) 8

  9. HF Repair/Upgrade for Phase 2(if so decided…) • A replacement of (at least a fraction of) QPF with QQF may be necessary (if feasible) • provided safe procedures for manipulation of HF activated parts are implemented, • with investments comparable to the original costs of HF fibers and PMTs (~2.5 M and ~1 M respectively in 2000-01 CHF; at that time 1 USD was ~1.7 CHF). • The cost for QQF fibers assumes replacement of about 20% of the QPF, at about 5 times their original price. • If manipulation of activated components, for fiber extraction and stuffing, turns out to be prohibitive, • replacement of full absorber matrix should be considered, possibly including a finer-grained configuration, for instance to provide smaller trigger tower size, if useful. • The price tag in 2000 of original steel wedges with electro-etched grooves and diffusion welding assembly was ≤ 1 MCHF. 9

  10. Someveryhighluminosity options and alternatives • Liquid Č Radiator / Scintillator [V. Bonvicini et al, E. Norbeck] • Gas Č Radiator [M. Albrow, D. Kaefer](ILC Č Detector) • Gas Ionization (PPAC) [Y.Onel, E. Norbeck] • Secondary Emission [Y.Onel, D.Winn] • Rad-Hard detectors (Si, GaAs, Diamond (?) /W ) (SiD/ILD Forward Calorimetry) • Quartz Plate with enhancement technology ( Zn O, pTp) [Onel, Cremaldi, Winn] 10

  11. [Just one example:] Liquid Scintillator in Quartz Tubes [V. Bonvicini et al.: Compensating Calorimeters for High Luminosity Experiments Based on Liquid Scintillator Contained in Quartz Tubes] (INFN –Trieste Report [FACTOR-2009]) • Extreme radiation doses require use of radiation-hard materials, and/or replaceability of those parts of the calorimeter which are not radiation hard. • It has been suggested (A. Artamonov et al.[1], K. Pretzl, …) that liquid scintillators would be easily refillable into calorimeters • Liquid scintillators in quartz tubes would additionally allow use of both scintillation and Čerenkov light from the quartz tubes, in order to achieve event-by-event compensation in the calorimeter response. • A. Artamonov et al. A Liquid Scintillator Calorimeter for the Forward region of an LHC Experiment (1991) 11

  12. plug/manifold Grooved Absorber Plate Liquid Scintillator-QuartzTube Arrays For example: • 3-5mm  quartz tube • 0.7mm thick wall • filled with liquid scintillator See also: • F. Garufi: Nuovi rivelatori di particelle a scintillatore liquido per calorimetria e tracciamento ad alta risoluzione Tesi Dott. Ricerca, Dip. di Fisica, Univ. Federico II, Napoli (1996) • Each tube is connected to a plug/ manifold which allows the liquid scintillator flow through quartz tubes, connected to distribution &purge system; photodetectors are on the transparent back side of the plugs. 12

  13. Conclusions • Baseline for HF upgrade in Phase 2 • replace (about 20% of) QPF with QQF • …PMT replaced earlier… (?) • If HF activation prohibits manipulation • construction of new modules • may give opportunity for new options • Should we "…leave the old road for a new one…" ? "Chi lascia la via vecchia per la nuova… …sa cosa lascia, ma non sa cosa trova…" 13

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