Beam Loss: New Developments, Detectors and Electronics Bernd Dehning CERN BE/BI Event triggered beam loss measurements with diamonds Accuracy of loss simulations (Geant4, Fluka) Detector development for loss measurements at 2 Kelvin Development of low pressure ionisation chamber Acquisition electronic, high dynamic range, radiation tolerant 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning Nano second response time Large dynamic range Operation at 1.8 Kelvin 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Ionisation Characteristics in 500 um sCVD Courtesy to E. Griesmayer 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

4 Diamond BLMs for Observation at LHC (event triggered) ATS/Note/2011/048 (TECH), B. Dehning et al. Chemical Vapor Deposition (CVD) diamond IP7 collimators (TCP) – one per beam All sizable local losses are also seen at collimators Injection regions – one per beam 40 dB amplification 2 GHz upper limit Dose up to 1 MGy Risetime 180 ps Pulse width 300 ps Fall time 400 ps SNR of 5 with 1.6 fC Courtesy E. Griesmayer

LHC: 152 bunches, 150ns bunch spacing (3/10/2010 12h48) Time Loss signal due to macro particle collision loss due extraction kicker imperfection Figure 25: The 10 ms buffer (1 ms/div) shows the characteristics of event and turn-­clock signal LHC (89.2 us). dump causes a high pulse at end loss pattern.

LHC: 152 bunches, 150ns bunch spacing (3/10/2010 12h48) Loss signal Time Diamond signal Figure 26: Zoom factor 101 (100 us/div): the time structure of bunch trains can be estimated. The corresponding measurement from ionization chambers is shown at bottom and shows an excellent agreement between DBLM chambers. Ionisation chamber (40 us integration time)

LHC: 152 bunches, 150ns bunch spacing (3/10/2010 12h48) Loss signal Time

LHC: 152 bunches, 150ns bunch spacing (3/10/2010 12h48) Loss signal Time

LHC: 152 bunches, 150ns bunch spacing (3/10/2010 12h48) Time Loss signal About 20 particle per pulse

Comparison of Loss Simulations and Measurements Steady state loss Relative differences max 100 % Loss duration about 10 ms More geometry details included in MQY and MBRB simulations (lower comparison)

Particle shower simulations (more Details) The LHC Beam Loss Monitoring system - PH Detector Seminar, 201.06.10 Collimation workshop, 2011.06.15 Is the BLM system ready to go to higher intensities? - Chamonix 2011 07.09.2010 One of the most spectacular quench tests: generate millisecond scale losses using with Wire Scanner at 3.5 TeV. FLUKA simulations Max Edep FLUKA: 62.5 mJ/cc QP3: 38 mJ/cc (preliminary) we call it a good agreement 07.09.2010 11 IP8 Shower simulation could be accurate to few 10% in transverse tails of 20 to 30 cm 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning 11

Ionisation Chamber Response Function Simulations LHC 1.5 liter chamber: Function are available for 10, 30, 45, 60 and 90 degree Small differences between FLUKA and Geant4 are seen for low energies (< keV) Response functions of Ionisation Chamber Beam Loss Monitor, M. Brugger, E. Lebbos, M. Sapinski, M. Stockner; EDMS 1055210; 2010 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Motivation for the Development of Detectors Operating at 2 Kelvin BEAM Over 3 order of magnitude difference between energy deposition in coil and outside cryostat detectors Detector in the cold (LHC triplet) 2 order of magnitude difference between energy deposition in coil and outside cryostat detectors Energy deposition in the detectors follows closer deposition in the coil

Dose Measurements at 2 Kelvin IFMIF (LIRA) ITER material studies New LHC quadrupole magnet Location of detectors Steering of beam to minimize energy deposition in cavity (Courtesy J. Marroncle) Initiating of beam abort trigger 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Diamond and Radiation Hardness Top: sCVD shifted to the left to show that it follows the same degradation parameterization as pCVD Bottom: sCVD irradiation loss: 20 % of initial signal drop of signal to noise from 26 to 7 From: W.Trischuk & RD42, “Resent advances in diamond detectors” From “Fast beam conditions monitoring (BCM1F) for CMS” by N/Bernardino Rodriguess, … 1.5 E17 1/cm2 (MIP) No data are available at temperatures below 100 Kelvin 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Poly and single crystalline CVD (Diamond) Detectors Courtesy to E. Griesmayer, CIVIDEC 20 mV/div stopped after few um 10 mV/div pCVD faster but less signal compared to sCVD traverse the detector 10 mV/div 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Measurement Set-UP – beam PS – Proton 20 GeV liquid He Chamber 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning Integration over length of spill (400 ms) Leakage current below 1 pA Test of radiation tolerance foreseen for June & Nov. 2011 (dose: 1MGy, few E15 prot/cm2) Signal integration over 0.6 seconds Average response of single particle Christoph Kurfuerst, CERN BE-BI 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Si Studies with Pulsed LASER (100 ps duration) I CVD 500 um thickness 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Si Studies with Pulsed LASER (100 ps duration) II Drift velocity is constant up to 40 Kelvin Drift velocity variation (saturation to 300 K) for holes by a factor 3 and for electrons by a factor 2.4 Saturation plateau shows some variation (hypothesis shallow energy level capture charges) General: for steady state irradiation and radiation damaged material polarisation effects expected. 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Ionisation Chamber Time Response Measurements (BOOSTER) Chamber beam response Chamber current vs beam current slength proton= 50 ns 80 % of signal in one turn Intensity discrepancy by a factor two FWHMe-= 150 ns Intensity density: - Booster 6 109 prot./cm2, two orders larger as in LHC 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning Ionisation Chamber Energy Deposition Measurements and Geant4 Simulation Test in SPS T2 extraction line 400 GeV protons, medium intensity (quench levels) Chamber moved through the beam Structure of chamber reproduced Integral difference between measurements and simulation about 25 % beam 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Low Pressure (0.4 bar) Ionisation Chamber Measurements Test Set-Up Top left: LHC Steady state losses in collimation area Bottom left: BOOSTER fast response (100ns) and high intensity beam (200 ns, 2A peak IC) Top right: CNGS medium response 20us, 1 mA peak IC) 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Low Pressure (0.4 bar) Ionisation Chamber (LIC) Measurements SEM - LIC SEM - LIC LHC: LIC - IC BOOSTER BOOSTER IC - LIC IC - LIC LIC shows at about 1E10 smaller peak and long tail compared to IC (width increase) Sensitivity ratio between chambers as expected Linearity at low and high tested BOOSTER BOOSTER BOOSTER BOOSTER 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning LHC tunnel card Not very complicated design “simple” Large Dynamic Range (8 orders) Current-to-Frequency Converter (CFC) Analogue-to-Digital Converter Radiation tolerant (500 Gy, 1 107 p/s/cm2) ADC custom ASIC Triple module redundancy Reset time Integration time V out I + I - Threshold Comparator 100 ns 100 ns to 100 s 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Current to Frequency Converter circuit limited by: 1. leakage currents at the input of the integrator (< 2 pA) 2. fast discharge with current source (<500 ns) dynamic of arc monitors 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Advanced Current to Frequency Converter Principle LHC current to frequency converter: only positive signals (limitation in case of signal under shoots) 500 Gy radiation tolerance Reference current source Integrator Comparator f = Iinput / (Iref * Tref) 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Advanced Current to Frequency Converter Principle LHC current to frequency converter: only positive signals (limitation in case of signal under shoots) 500 Gy radiation tolerance Reference current source Integrator Comparator f = Iinput / (Iref * Tref) 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Advanced Current to Frequency Converter Principle LHC current to frequency converter: only positive signals (limitation in case of signal under shoots) 500 Gy radiation tolerance Reference current source Integrator Comparator f = Iinput / (Iref * Tref) 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Advanced Current to Frequency Converter Principle LHC current to frequency converter: only positive signals (limitation in case of signal under shoots) 500 Gy radiation tolerance Reference current source Integrator Comparator f = Iinput / (Iref * Tref) 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Fully Differential Current to Frequency Converter Principle Discrete components: not radiation tolerant Specifications: Dynamic range 7 orders integration window 2 us 1nA to 200mA Dynamic range 9 orders integration window 1 s 10pA to 200mA A status signal selects in which branch of a fully deferential stage the input current is integrated. Two comparators check the differential output voltage against a threshold, whenever is exceeded, the status signal changes to the complementary value (0 ! 1 or 1 ! 0) and the input current is integrated in the other branch. Input switch Fully differential Integrator Bidirectional digitalisation; optical and Ethernet link 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Fully Differential Current to Frequency Converter Diagram Input 50 ohm resistor split in two: 47 + 3 ohm Re-routing on the ADC buffer amplifier ADC input shunt resistor switches ADC shunt or CFC operation CFC switches for CFC 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Fully Differential Current to Frequency Converter Diagram Input 50 ohm resistor split in two: 47 + 3 ohm Re-routing on the ADC buffer amplifier ADC input shunt resistor switches ADC shunt or CFC operation CFC switches for CFC 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Fully Differential Current to Frequency Converter Top: PSpice simulation of CFC part of circuit Bottom: first test circuit results Printed circuit boards test in the next weeks To be used for the beam loss system in the CERN pre-accelerators 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

CMS BCM1F Monitor System (histogram of loss arrival time) See Elena Castro talk Radiation tolerant ASIC amplifier and laser diodes Detector and electronics mounted in a few centimeter case VME based CAEN module acquisition system ADC 500 MHz Scalar TDC Next project: increase of dynamic range and transmission link optimisation DESY Zeuten – CERN BE/BI 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Acquisition System Specification for Diamond Signal Two data sets should be available: Signal versus time Number of signals over threshold versus arrival time Next project: compact diamond signal acquisition system; industries - CERN Detector Pulse Amplitude Max. 2 V Min. 1 mV width 5 ns time jitter noise level below Double pulse resolution 20 Digitalisation of the signal ADC (min) 10 bit range sampling 500 MHz bandwidth 250 Buffer 1.00E+007 words Trigger input TTL Histogramming of arrival times Threshold DAC min 0.5 Reference frequency kHz max Histogram 5.00E+004 bins Signal frequency Signal to be measured Oscilloscope features Market survey has been started Histogram of time of arrival

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning Reserve Slides 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss Detectors used at CERN Ionisation chambers Aluminium Kathode + PM N2 @ 1.2 bar Secondary Emission effect N2 @ 0.4 bar Cherenkov Light + PM Optical fibre + SiPM (array) CLIC + Proton transfer Diamond pCVD + sCVD pCVD amplifier 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Ionisation Chamber and pCVD Comparison Diamond pCVD shows after pulse some long tails Ionisation chamber shows no tail Leakage current Ionisation chamber < 1pA CMS pCVDs most few tenth of pA one up to 1 nA (S. Mueller) CMS: S. Mueller 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Diamonds Signal over Threshold and Arrival Time Histogram Non colliding bunche Empty bunch region Courtesy S. Mueller bunch number Measurement of bunch filling scheme with high dynamic range Model reproduces measurements 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Arrival Time Histogram from Losses downstream of Collimator Measurement set up allows details study of loss origin Losses from beam and interaction debris from the LHCb experiment Counts Losses from beam approaching the LHCb experiment 25 ns bunch spacing 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Post Mortem Data (some examples) Loss in a bending magnet PM application: BLM data of 0.082 sec online available Longer PM buffer: BLM data of 1.72 sec offine available 43000 values (40 us) Monitors 2000 values (40 us) Time 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Post Mortem Data (some examples), Zoom Loss from primary event + dump system loss 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

1.8 Kelvin Loss Detection – MIP response (20 GeV Protons) Si at 1.8 K Si at 4.2 K Diamond (sCVD) Open questions: radiation hardness, DC current value, non linearity effects for high losses 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning ALPHA source sCVD 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning CERN IC 54 uC/Gy LIC 1.4 uC/Gy CERN CERN 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Ionisation Chamber and Secondary Emission Monitor Stainless steal cylinder Parallel electrodes distance 0.5 cm Diameter 8.9 cm Voltage 1.5 kV Low pass filter at the HV input Signal Ratio: IC/SEM = 60000 IC: Al electrodes Length 60 cm Ion collection time 85 us N2 gas filling at 1.1 bar Sensitive volume 1.5 l SEM: Ti electrodes Components UHV compatible Steel vacuum fired Detector contains 170 cm2 of NEG St707 to keep the vacuum < 10-4 mbar during 20 years 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning BCM1F 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning

The BLM Acquisition System (ALL Experiments and LHC) Range 1 pA to 1 mA Radiation tolerant to 500 Gy SEE tested Analog front-end FEE Current to Frequency Converters (CFCs) Analogue to Digital Converters (ADCs) Tunnel FPGAs: Actel’s 54SX/A radiation tolerant. Communication links: Gigabit Optical Links. Real-Time Processing BEE FPGA Altera’s Stratix EP1S40 (medium size, SRAM based) Mezzanine card for the optical links 3 x 2 MB SRAMs for temporary data storage NV-RAM for system settings and threshold table storage Beam Loss: New Developments, Detectors and Electronics ; B.Dehning 05.12.2011

Beam Loss: New Developments, Detectors and Electronics ; B.Dehning 05.12.2011 Beam Loss: New Developments, Detectors and Electronics ; B.Dehning