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Beam Loss Monitors

Beam Loss Monitors. B. Dehning. Some remarks. Capacitors test with high dose Damage threshold on collimator Transient losses: Alfredo, Steady state losses: xxx SC link transient losses value?. LHC Radiation Fields. Radiation spectra are very similar Radiation levels in [cm -2 Gy -1 ]

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Beam Loss Monitors

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  1. Beam Loss Monitors B. Dehning LHC Radiation Day, B. Dehning

  2. Some remarks • Capacitors test with high dose • Damage threshold on collimator • Transient losses: Alfredo, • Steady state losses: xxx • SC link transient losses value? LHC Radiation Day, B. Dehning

  3. LHC Radiation Fields • Radiation spectra are very similar • Radiation levels in [cm-2 Gy-1] beampipe with cryostat 6 x 1010 n > 100 keV 4 x 109 h > 20 MeV 2 x 109 h > 100 MeV beampipe 4 x 109 n > 100 keV 8 x 108 h > 20 MeV 5 x 108 h > 100 MeV • Annual dose • 1-2 Gy alongside magnets, 10-20 Gy in inter magnet gaps • 35-150 Gy in dispersion suppressors, 9 kGy in cleaning sections C. Fynbo, LHC seminar 22/11/01 LHC Radiation Day, B. Dehning

  4. Radiation in the LHC J. Vollaire et al. "Calculation of Water Activation for the LHC, Proc. AccApp05 LHC Radiation Day, B. Dehning

  5. Parameterisation of a complex radiation field h > 20 MeV Single Events h > 100 KeV EM cascade nuclear cascade Displacement SEU counter Dose radiation damage semiconductors PIN Diodes Radfet Radiation Monitor LHC Radiation Day, B. Dehning

  6. Radiation Sensors per monitor • Dose, dose rate • Tyndall Radfets – 2 different types at a maximum of 1 rad/bit • Hadron flux, hadron fluence • TC554001AF-70 SRAM – 4 x 4 Mbit gives 1 SEU per 1 106 n > 20 MeV • 1 MeV eq. neutron fluence • SIEMENS BPW34FS – 3 diodes at maximum of 5 109 neutrons/bit (1 MeV) LHC Radiation Day, B. Dehning

  7. SEU counter design specifics • Comparison per “byte”, reference pattern “0” • 3 V or 5 V operation (3 V most sensitive) • Cycle time variable (to deal with frequency effects in SRAM) • read, write, compare 215 nsec – 1 ms • total scan (16 Mbit SRAM) 450 ms – 2100 ms • 2 x Triple redundant counting registers • Readout speed 3 counters via fieldbus over 2.5 km (6 actions : LSB1 FREEZE - MSB1 – LSB2 - MSB2– LSB3 - MSB3) • 4 kHz - 1 monitor • 100 Hz - 32 monitors LHC Radiation Day, B. Dehning

  8. Induced Activity Monitors Example of dose rate decrease monitoring Beam on Typical graph used to plan interventions (Work and dose planning) Beam off LHC Radiation Day, B. Dehning

  9. PE hull (4mm) / inside graphite coated Active volume 15.8 cm Anode: PE / graphite coated 21.5 cm 28.5 cm Connector to cathode Connector to anode Connector plug for power supply and signal outlet Induced Activity Monitors Main characteristics • Measure the ambient dose equivalent and ambient dose equivalent rate in photon fields (beam off); • Plastic ionisation chamber (3 litres, 1 atm. Air-filled); Manufactured by PTW Freiburg; • Performances : • Measuring range : 5 µSv/h to 500 mSv/h • Energy range : 50 keV to 7 MeV • Measuring time : from 1 to 3600 s Typical value 60 s • HV = -1 kV [2] Reference H. Vincke et al. LHC Radiation Day, B. Dehning

  10. Protected Area Tunnel or Experimental areas Average length = 200 m (min =50 m, max = 750 m) Remote readout Electronics Detector CERN *SPA6 cable (CERN design) Induced Activity Monitors Very low current over long distances HIGH RADIATION FIELDS during BEAM ON  REMOTE ELECTRONICS Measure current ranging from 100 fA up to 10 nA at a distance up to 750 m *SPA6 cable registered by CERN Technology Transfer Group LHC Radiation Day, B. Dehning

  11. Measurement of dose at a copper target intercepting beam (120 GeV/c) The fluence spectra close to the beam loss points in the LHC will be similar to those present at the CERF experiment RPL1 RPL2 Al2 Al1 Comparison between simulation and measurement presented last year. Agreement very good.  Dose close to beam loss point can be measured in a reliable way. LHC Radiation Day, B. Dehning

  12. CERN irradiation facilities LHC Radiation Day, B. Dehning

  13. External Facilities pi, p, n, ion LHC Radiation Day, B. Dehning

  14. External facilities, gamma LHC Radiation Day, B. Dehning

  15. Robustness of IR3/IR7 Collimators • Acceptable beam loss to regular machine equipment and metallic absorbers: • 1e12 p at injection: 4e-3 of beam • 5e9 p at 7 TeV: 2e-5 of beam • Acceptable beam loss to C-C collimators/absorbers: • 3e13 p at injection: 10% of beam • 8e11 p at 7 TeV: 3e-3 of beam • Maximum allowed loss rates at collimators (goal): • 100 kW continuously. • 500 kW for 10 s (1% of beam lost in 10s). • 1 MW for 1 s. 100 times better robustness! LHC Radiation Day, B. Dehning

  16. Shielding and Radiation to Electronics Gy/y K. Tsoulou et al, LHC Project Note 372 LHC Radiation Day, B. Dehning

  17. LHC Radiation Day, B. Dehning

  18. Location of Loss Detectors at IP8 left right • At every element several detectors mounted on: • cryostat • support • Detectors: • Ionisation chambers • Secondary emission LHC Radiation Day, B. Dehning

  19. LHC Radiation Day, B. Dehning

  20. LHC Radiation Day, B. Dehning

  21. [LPR500] [LPR500] BACKGROUND SOURCES • SOURCES CONSIDERED [LPN258] • The “DISTANT” sources • Collimation “inefficiency”  Out-scattered halo not intercepted by the collimators of the CS insertion • Elastic scattering in the cold sectors between IR and CS insertion Elastic beam-gas Cleaning • ONLY “elastic” products will be transported downstream by the optics! • Interactions with residual gas in the IR  both elastic and inelastic • Collisions in the neighbouring IP • P1IR8 probability distribution Vadim Talanov CERN November 29 2005

  22. TCTH TCTV [LPN371] NO QUENCH - NO BACKGROUND ? • TERTIARY BACKGROUND • The source is the halo out scattered from the IR7 and cleaned in the IR8 by the TCTs • Two tertiary collimators in each part of LSS8 • Vertical TCT at D1, horizontal at D2  D2-D1 is the longest drift in SS • Heavy (tungsten) collimators Scoring plane IR7 • FORMULATION OF THE PROBLEM • TCTs are here to protect D1-Q1 from quench  an aperture limitation in the IR • The “cleaned” protons will be converted toa “tertiary” background towards the IP LPN371: for elastic beam-gas losses TCTs in IR1 are the dominant background source Vadim Talanov CERN November 29 2005

  23. TOTAL PARTICLE FLUX • Charged hadrons Muons • VH@TCTV 3,66x106 1,05x106 • HH@TCTH 1,26x105 5,15x104 • LPN307 • LPN307 TERTIARY BACKGROUND (1) • SECONDARY PARTICLE FLUX AT THE IP8 • Source: loss maps generated within Collimation Project Vertical halo in TCTV and horizontal in TCTH Re-normalised for the 30 hours beam lifetime  LPN273: “1,03x106 muons/s … under the “3rd year +90days” LHC running conditions…” • RADIAL DISTRIBUTION • Particle flux density f(r)[particles/cm2/s] • For charged hadrons/muons • Compared with LPN307  beam-gas estimates forNO SHIELDING case • TOTAL • TOTAL • TCTV • TCTH • TCTH • TCTV Vadim Talanov CERN November 29 2005

  24. Shielding Shielding SS8L P8 Q1 BACKGROUND SHIELDING • SHIELDING PLUGS IN THE IR2/8 • Detector protection from the background as inner/forward shielding at the P1/5 • Proposed in 2002 [LPN307] • The closer to IP/beam line – the better  Several installation constraints! • Specific design for left/right parts of SS • The possibility of a “staging” approach Vadim Talanov CERN November 29 2005

  25. BACKGROUND SHIELDING • Charged hadrons Muons • VH@TCTV 3,66x106 1,05x106 • 4.51x104 2.71x105 • HH@TCTH 1,26x105 5,15x104 • 3.21x103 2.72x104 TERTIARY BACKGROUND (2) • BACKGROUND IN THE PRESENCE OF THE SHIELDING • Combined model of simulations Same maps of the losses in the TCTs Shielding introduced in the left part of the LSS8 Results compared to the previous TOTAL numbers • EFFECT OF THE SHIELDING • Charged hadrons fluxremoved at large radii • Reduction factors charged hadrons: ~ 100 muons: 2÷4 (depending on halo type) • …minor effect aroundvacuum chamber… • No shielding • No shielding • With shielding • With shielding Vadim Talanov CERN November 29 2005

  26. Minutes Reports LHC MIB WORKING GROUP • MACHINE INDUCED BACKGROUND WG • Forum on Detector Protection and Background Shielding • Established in 2005 by TS/LEA • Complex study of MIB problem  Analysis of the background formation Prediction of the dynamics at different stages of machine operation Reduction and rejection from the signal • COLLABORATION WITH OTHER GROUPS • The study of the machine background is cooperative • Collimation project • Vacuum group • Experimental collaborations • More information on WG pages at: cern.ch/lhc-background Vadim Talanov CERN November 29 2005

  27. European Space Components Information Exchange System See: https://escies.org Radiation

  28. Radiation levels • Radiation levels in detectors and cavern simulated with Fluka and Mars (crosschecked) • Simulation safety factor: 2 (rather low) • Total Ionizing Dose, • 1Mev neutrons • Hadrons above 20MeV (SEU, SEL, SEB) • Clearly defined radiation hardness requirements for 10 years operation for all locations with electronicsweb page: http://lhcb-background.web.cern.ch/lhcb-background/Radiation/SUMtable2.htm • Location TID/rad Neu/cm2 Hadrons/cm2 • Velo & Pileup 10M 1014 1014 • IT & Muon 1M 1013 1013 • RICH1 front-end. 25k 3*1012 3*1011 • Muon crates 10k 1012 5*1010 • Cal crates 4k 1012 3*1010 • Bunker 1k 1012 3*1010 • Balcony 650 3*1011 6*109 Total dose inside experiment Z X Gray/year Ecal detector TID Neutrons Racks LHC Radiation Day,

  29. Radiation hardness policy • Radiation hardness policy defined and agreed upon with all sub-systems from the beginning (at same time as defining front-end architecture) • This took some time and we all had to educate our selves in this field that was new to many (1999 – 2001) • Multiple meetings and workshops • Ratified by LHCb technical board (2001) • Radiation level simulations made • MARS: 1999 – 2000 • FLUKA: 2001 – 2003 (still ongoing for locations with changes, e.g. LHC machine equipment) • Safety factors • Simulation: 2 • Components: ~10 (In certain cases we have had to accept lower values for this) • Testing: 2 (lower if justified) • Failure types and rates: • Different risk factors in different locations (SEL, SEB) (accessible or not) • Different types of data (SEU): • Event data itself does not need SEU protection (like a bit of extra noise) • Event headers should be protected (system synchronization) • Control state machines must be protected • Configuration must be protected • Control interfaces must be very reliable (used to recover system when problems) • Reset procedures • Qualification procedure (profiting from work done by ATLAS/CMS) • All circuits used in detector and cavern MUST be radiation tested • Verified during reviews LHC Radiation Day,

  30. Radiation hard/tolerant electronics • In detectors: ASIC’s • ~12 LHCb specific ASIC’s • Most implemented in 0.25um CMOS with radiation hard layout (enclosed transistors) and triple redundant storage elements in critical parts (configuration and control logic) • A few chips in 0.8 um BiCMOS • Radiation tests performed • Use of LHC generic radiation hard circuits: TTCrx, GOL, QPLL, Delay25, linear power regulator • In cavern or on periphery of detectors: Use of Commercial Of The Shelves (COTS) components in many cases possible. • Circuits must be tested or find reliable radiation test elsewhere (HEP, SPACE) • Total dose in most cases not problematic (modern CMOS) • Single event latchup problematic and must be avoided (with one exception in LHCb) • Neutrons does not affect modern CMOS circuits • Neutrons could be problematic for optoelectronics • SEU rates must be estimated to predict system reliability (not so easy) • Triple redundant logic in central functions (control, ECS) and when ever possible. • Problem of traceability between tested circuits and final circuits mounted on boards. • Significant time delay ( 1 - 2 years) between purchasing test samples and final quantities • Difficult to verify that circuits are made with identical processing • Change of Fab. ? • Internal/external second sourcing • We have been forced to take this risk • Doing our best to verify that technology and fabrication line have not changed. LHC Radiation Day,

  31. Commercial electronics (COTS) • Two types of FPGA’s have been found appropriate for use at limited (~10krad) radiation levels in cavern • Antifuse FPGA: • No problem with corruption of configuration (general reliability of antifuse have been problematic in the past) • But can not be reconfigured either (nearly like an ASIC) • No SEL seen in radiation tests of new antifuse series • Triple redundant registers needed for critical parts • Flash based FPGA • Flash configuration does not get corrupted • No SEL seen in latest series (proASIC+) • Triple redundant registers needed for critical registers • General infrastructure logic may though be problematic (startup, JTAG) • Small part of chip and therefore very small cross-section • We do not want to use SRAM configuration based FPGA’s (e.g. Xilinx) • It has been seen that chips in same technology and same chip family has had different behavior (SEL) • In one case an ADC with a potential SEL problem (seen with ions) has dedicated external protection circuit with self recovery. • 12 way optical transmitter seen to have small cross section of short link errors from “SEU” • This could de-synchronize our readout/trigger and be problematic as 7000 optical links used in LHCb • Enforced use of link idles to resync links on the fly. • We do not want to use microcontrollers , PLC’s and CPU’s in experimental cavern. • One exception with ELMB having a dual checking processor and software with watchdogs (ATLAS development and qualification) • I personally have some small worry on this, but mainly used for environment monitoring Calorimeter board LHC Radiation Day,

  32. 0.5 m 30 m 60 m 10 m Wall 12 links ribbon cables 8 ribbon cables MPO-MPO MPO-SC Cassette Breakout cable transmitter 12 way fiber ribbon receiver Optical links • ~7000 optical links: L0 trigger and Readout links • GOL radiation hard serializer from CERN-MIC at 1.6Gbits/s • Single link transmitters with VCSEL directly modulated by GOL • 12 way link transmitters using fiber ribbon optical modules • 12way fiber ribbon receivers • Deserializers: TLK2501, Stratix GX FPGA, Xilinx Vertex 4 FPGA. • All receivers in counting house • Extensive qualification of links by individual groups • Standardized (and simplified) LHCb qualification procedure • GOL built in test pattern generator (counter, not pseudo random) • Bit error rate below 10-12 with additional 6db optical attenuation (1/2 hour test) • BER to be measured for 9db and 12db attenuation • Link errors (bit, word and desync) could be problematic in final system • One 32 bit idle word enough to resynchronize link. • All L0 trigger links resynchronized in the large LHC bunch gap • All readout links have sufficient idles between each event fragment to allow link to resync (not if PLL lost lock) LHC Radiation Day,

  33. Radiation damages to cryogenic equipment (I) From the radiation simulation results and irradiation tests • Automates and Remote I/Os • 1 functional interrupt per day, • ‘Hard’ Single Events in modular power supplies , • ‘Soft’ Single Events in PLC and “intelligent” I/Os. • Electro-pneumatic valve positioners (ref. tests of W. Hees- AT/ACR): • - in QURC (top and beam level platforms): • 1 critical erratic valve position every 11 days (beam dump). • - in QUI (ground level): • 1 critical erratic valve position every 77 days (beam dump). 5th LHC Radiation Day

  34. Total Ionizing Dose Cryo equip. radial axis 1300 TID [Gy] transversal axis X [cm] platform TID [Gy] beam axis IP Z [cm] radial axis (radial distance from the beam axis) beam axis magnet ECAL-HCAL muons chambers TID @ cryo equip. : 1-10 Gy for 10 LHC years Horizontal cross-section @ beam level (y=0m) Top-view 5th LHC Radiation Day

  35. 1 MeV n. equiv. fluence- Displacement damage 1 MeV n. equiv [cm -2] beam axis radial axis (radial distance from the beam axis) Horizontal cross-section @ beam level (y=0m) Top-view Cryo.Equip. 1300 radial axis 1 MeV n. equiv [cm -2] X [cm] platform IP Z [cm] beam axis magnet ECAL-HCAL muons chambers 5th LHC Radiation Day 1 MeV n. equiv. @ cryo equip.: 10 11 – 10 12 /cm2 for 10 LHC years

  36. Hadrons (E>20MeV) fluence- Single events Horizontal cross-section @ beam level (y=0m) Top-view Cryo. Equip. 1300 hadrons (E>20 MeV) [cm -2] radial axis X [cm] platform hadrons (E>20 MeV) [cm -2] beam axis IP Z [cm] radial axis (radial distance from the beam axis) beam axis magnet ECAL-HCAL muons chambers 5th LHC Radiation Day Hadrons (E >20 MeV). @ cryo equip.:10 9 – 10 10 /cm2 for 10 LHC years

  37. TOTAL IONISING DOSE TESTS Gamma (60Co) facility, CIS-BIO International CEA Saclay • PAGUREirradiator: (activity ~14 kCi) • Dose rates: • 30 Gy/hr to 1 kGy/hr (large volumes) • 30 Gy/hr to 20 kGy/hr (small volumes) • POSEIDONirradiator: (activity ~1 MCi) • Dose rates: • ~ 2 kGy/hr LHC Radiation Day,

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