29.11.2005LHC Radiation Day, B. Dehning1 Beam Loss Monitors B. Dehning

29.11.2005LHC Radiation Day, B.

Dehning 1

Beam Loss Monitors

B. Dehning


Dehning 2

BLM Locations in the Arcs

3 loss locations simulated: shower development in the cryostat, GEANT 3 & 4.

The positions of the BLMs are chosen to: minimize crosstalk reduce difference between inside and outside loss

BLM positionLoss location


Dehning 3

Location of Loss Detectors at IP8

At every element several detectors mounted on:

cryostat support

Detectors: Ionisation

chambers Secondary

emission

N. Location IC SEM

1 BPMSW.1L8 1 12 MQXA.1L8 63 MQXB.A2L8 64 MQXA.3L8 65 TCTV.4L8.B1 1 16 TCLIA.4L8.B2 1 17 TCTH.4L8.B1 1 18 MBRC.4L8 1 19 MQY.A4L8 6

10 MQM.A5L8 611 TCLIB.6L8.B2 1 112 MQML.6L8 613 MQM.A7L8 614 MBA.8L8 6

MBA.8L8 615 MQML.8L8 616 MQM.9L8 617 MQML.10L8 618 MBA.11L8 6

MBA.11L8 619 MQ.11L8 6

20 MQ.12L8 621 MQ.13L8 622 MQ.14L8 623 MQ.15L8 624 MQ.16L8 6

N. Location IC SEM

1 BPMSW.1R8 1 12 MQXA.1R8 63 MQXB.A2R8 64 MQXA.3R8 65 TCDD.4R8 3 36 TCTV.4R8.B2 1 17 TDI.4R8 3 38 TCTH.4R8.B2 1 19 MBRC.4R8 1 1

10 MQY.A4R8 611 MQY.A5R8 612 MSIA.A6R8 3 313 MSIB.A6R8. 3 314 MQM.6R8 615 MQM.A7R8 616 MBA.8R8 6

MBA.8R8 617 MQML.8R8 618 MQM.9R8 619 MQML.10R8 620 MBA.11R8 6

MBA.11R8 621 MQ.11R8 6

22 MQ.12R8 623 MQ.13R8 624 MQ.14R8 625 MQ.15R8 626 MQ.16R8 6

left right


Dehning 4

Ionisation chamber LHC Stainless steal cylinder Parallel electrodes separated by

0.5 cm Al electrodes Low pass filter at the HV input N2 gas filling at 100 mbar over

pressure Diameter 8.9 cm Length 60 cm Sensitive volume 1.5 l Voltage 1.5 kV Ion collection time 85 us


Dehning 5

LHC acquisition board Current to Frequency

Converters (CFCs) Analogue to Digital

Converters (ADCs) Tunnel FPGAs:

Actel’s 54SX/A radiation tolerant.

Communication links:Gigabit Optical Links.

Surface FPGAs: Altera’s Stratix EP1S40 with 780 pins.

8 channels multiplexed

Redundant optical link


Dehning 6

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 1012 p/cm2) Bipolar Customs ASICs Triple module redundancy Reset time Integration time

V out

I +I -

ThresholdComparator

100 ns 100 ns to 100 s


Dehning 7

Current to Frequency Converter and Radiation

Variation at the very low end of the dynamic range Insignificant variations at quench levels Radiation caused offset by DAC induced current compensation

CFC2-TOTAL-0Gy-1000Gy

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03

I in [A]

f out

[Hz]

Ch2-CFC2-not-irr-1meas.Ch2-CFC2-not-irr-2meas.Ch2-CFC2-JFET-0GyCh2-CFC2-JFET-500GyCh2-CFC2-JFET-1000GyCh8-CFC2-not-irr-1meas.Ch8-CFC2-not-irr-2meas.Ch8-CFC2-JFETS-0GyCh8-CFC2-JFETS-300GyCh8-CFC2-JFETS-600GyCh4-CFC2-not-irr-1meas.Ch4-CFC2-not-irr-2meas.Ch4-CFC2-JFETS-0GyCh4-CFC2-JFETS-300GyCh4-CFC2-JFETS-600GyCh6-CFC2-not-irr-1meas.Ch6-CFC2-not-irr-2meas.Ch6-CFC2-JFETS-0GyCh6-CFC2-JFETS-300GyCh6-CFC2-JFETS-600GyCh8-CFC2-not-irr-1meas.Ch8-CFC2-not-irr-2meas.Ch8-CFC2-TOTAL-300GyCh8-not-irr-1meas.Ch8-not-irr-2meas.Ch7-not-irr-1meas.Ch7-not-irr-2meas.Ch5-not-irr-1meas.Ch5-not-irr-2meas.Ch3-not-irr-1meas.Ch3-not-irr-2meas.Ch1-not-irr-1meas.Ch1-not-irr-2meas.Ch1-CFC2-JFET-0Gy-not-irrCh1-CFC2-JFET-500Gy-not-irrCh1-CFC2-JFET-1000Gy-not-irrCh1-CFC2-JFETS-0Gy-not-irrCh1-CFC2-JFETS-300Gy-not-irrCh1-CFC2-JFETS-600Gy-not-irrCh1-CFC2-TOTA-300Gy-not-irr

Ch8-CFC2-TOTAL-0Gy-300Gy

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06I in [A]

f out

[Hz]

Ch8-CFC2-not-irr-1meas.Ch8-CFC2-not-irr-2meas.Ch8-CFC2-TOTAL-300Gy

Quench 7 TeV

Quench 7 TeV

2.5 pA to 1 mA50 nGy/s to 20 Gy/s


Dehning 8

CompareCRCs

Secondary B Signal(256 bits)

S/W & TTLoutput

Check CRCvalidity

DeMux

1 2 3 … 8

Truncateextra/redundant bits

(leave 160 bits)

Status10-bits

Primary A Signal (256 bits)

Only CRC

(4 byte)

Only CRC

(4 byte)

Signal Select(A or B)

ErrorError

Error

Error

Check CRCvalidity

Error

Reception______________ _ _

Tx Check&Signal Choice

______________ _ _

Tunnel Status Check______________ _ _

Format Data

______________ _ _

LHC transmission check

Signal Select TableCRC32 check Comparison

of 4ByteCRCs

Output RemarksA B

Error Error Error Dump Both signals have error

Error Error OK Dump S/W trigger (CRCgenerate or check wrong)

Error OK Error Signal B S/W trigger (error at CRC detected)

Error OK OK Signal B S/W trigger (error at data part)

OK Error Error Signal A S/W trigger (error at CRC detected)

OK Error OK Signal A S/W trigger (error at data part)

OK OK Error Dump S/W trigger (one of the counters has error)

OK OK OK Signal A By default (both signals are correct)

At the Surface FPGA:

Signal CRC-32 Error check / detection

algorithm for each of the signals received.

Comparison of the pair of signals.

Select block Logic that chooses signal to

be used Identifies problematic areas.

Tunnel’s Status Check block HT, Power supplies

FPGA errors Temperature


Dehning 9

Beam on FPGA, SEU & Transmission Errors check

Stop of transmission at 700 Gy (3 108

proton/s/cm2)

1. CRC errors on opt link B (red)

2. CRC A & B not equal (blue)3. CRC A errors (green)4. Loss of transmission B, A

(violet, blue)


Dehning 10

Test Procedure of Signal Chain

Basic concept: Automatic test measurements in between of two fills

Measurement of 10 pA bias current at input of electronic Modulation of high voltage supply of chambers

Check of components in Ionisation chamber (R, C) Check of capacity of chamber (insulation) Check of cabling Check of stable signal between a few pA to some nA (quench level region)

Not checked: the gas gain of chamber (in case of leak about 50 % gain change, signal speed change – to be checked)


Dehning 11

Some Specification Requirements DATA FOR THE CONTROL ROOM AND THE LOGGING SYSTEM

Loss rates normalized quench level, (energy and integration time-independent) (units need still to be defined)

Updated every second Allow frequency spectrum analysis Long term summation for comparisons with dose detectors

POST-MORTEM ANALYSIS Stored data: 100 - 1000 turns before post mortem trigger Average rates: a few seconds to 10 minutes before a beam-

dump False dumps

less than one per month (about 2 to 3 per month, simulations) BEAM 1/BEAM 2 DISCRIMINATION

If possible, higher tuning efficiency A set of movable BLM’s


Dehning 12

Beam Dump at HERA

Aim of setup BLM system test Verification of Geant

simulation Beam losses dynamic

observations LHC measurement

setup 6 chambers in top of

internal dump 1 before and 1 after

the dump


Dehning 13

Dose Measurements at the HERA Beam Dump

Protons: 1 1013

E = 920 GeV

Peak corresponds to 1.5 Gy


Dehning 14

Dose Measurements at the HERA Beam Dump, zoom


Dehning 15

SPS Ionisation Chamber Spectrum Response

Ionisation chambers:

H6 line measurements

HERA Dump Response to mixed

radiation field (chambers outside cryostat)

Comparisons with simulations (shown by H. Vincke)

Thesis M.Stockner SEM

Same procedure as for ion. ch.

BOOSTER PSI Thesis D. Kramer

Preliminary results longitudinal impact


Dehning 16

Reserve Slides


Dehning 17

LHC Bending Magnet Quench Levels, LHC Project Report 44

Quench energy density in SC coil

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

0.01 0.1 1 10 100 1000 10000 100000

loss duration [ms]

J/cm

3

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

Gy

Quench Energy [J/cm3] 7 Tev

Quench Energy [J/cm3] 450GeVdummy

Quench power in SC coil

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

0.01 0.1 1 10 100 1000 10000 100000

loss duration [ms]W

/cm

3

Quench Power[W/cm3] 7 TevQuench Power[W/cm3] 450 GeV

0.8 mJ/cm3 = 0.09 mJ/g (RHIC=2 mJ/g, Tevatron=0.5mJ/g)

38 mJ/cm3 = 5 mJ/g 5 mW/cm3 = 0.6 mW/g

(RHIC = 8 mW/g, Tevatron = 8mW/g)


Dehning 18

Systematic Uncertainties at Quench Levels

relative accuracies Correction means

Electronics < 10 % Electronic calibration

Detector < 10 – 20 % Source, sim., measurements

Radiation & analog elec. about 1 %

fluence per proton < 10 - 30 %

sim., measurements with beam (sector test, DESY PhD)

Quench levels (sim.) < 200 %measurements with beam (sector test), Lab meas., sim. fellow)

Topology of losses (sim.) ? Simulations


Dehning 19

Loss Levels and Required Accuracy

Relative loss levels450 GeV 7 TeV

Damage to components

320/5tran./slow

1000/25 tran./slo

w

Quench level 1 1Beam dump threshold for quench prevention

0.3 0.3/0.4 tran./slo

wWarning 0.1 0.1/0.25

tran./slow

Absolute precision (calibration)

< factor 2 initially: < factor 5

Relative precision for quench prevention

< 25%

Specification:

Accurately known quench levels will increase operational efficiency


Dehning 20

TT41 Beam DUMP Beam Dump design

similar to HEARA dump

Dose for impact of 450 GeV protons

Documents

29.11.2005LHC Radiation Day, B. Dehning1 Beam Loss Monitors B. Dehning