single shot test beam at ps ! simulation of a beam loss!

General Tracker Meeting 07/2002Frank Hartmann

1

Joint venture of CMS and ATLAS

Single shot test beam at PS!Simulation of a beam loss!

Joint adventure of CMS and ATLAS


Can we imagine a dump failure?

Some LHC numbers• Proton energy 7 TeV• Particles per bunch 1011

• Number of bunches 2835• Stored beam energy 336 MJ• Beam current 0.5 A• Failure: magnet quench; power converter fail, etc.

dipole or quadrupol failure decaying B-field need to dump

• Revolution time: 90µs• Abort gap: 3,17µs• Kicker rise time: 3µs

Can we even imagine a beam „lost“ in IP1 or IP5?


!!DUMP near to IP5 (CMS)!!

Mika Huhtinen:• Single module prefire:very unlikely

Assumption only one of the 14 abort kicker fires 4*10^13 protons lost in IP 5

• Unsynchronized abort: very likelyAssumption one of the dump kickers does not hit the abort gab bunch swept out for ~3µs; some deviated bunches

continue in the machine1*10^12 protons lost in IP 5

MC: STRUCT;MARS;FLUKA

IP5

IP6

LHC layout and hint for beamloss reason


Improbable things are not impossible!

• Both prefire and unsynchronized accidents happend at the TEVATRON!

• BUT: Less critical at the TEVATRON!

• They are improbable at LHC!!??!!

!RA EPAC02


Beam conditions at the PS8cm

cut• Fast extraction => spill ~ 100 ns duration

• Up to 1011 protons per spill (109 to 1010/ cm²)

• 24 GeV protons

• Beam spot: Starting 2-3cm diameter beam spot, but we expect to be able to tweak the last

quadrapole to have cigar shaped beam spot.– We are currently investigating if a 10cm diameter spot possible?

• Dosimetry to be handled by T7 group (secondary emission counter, gold or nickel foils).

• beam available for 8 hour shift, installation 1.5 days

• beam conditions fixed: 26.7.02


T7 Area


THE WHY!?!

• No integral effect expected (worst case = 10 days)

• But large instantaneous ionization! 1011 MIPS

1. Will our modules survive a beamloss?– Is our design robust?– Simple YES/NO test!

2. What is the dynamic behaviour?– Possible failure analysis!

ALL PARAMETERS will be dynamically checked slow (10µs) and fast (50ns) (Scopes/FADCs)


Specific Questions

1. Will the hybrid survive?2. ..............sensor survive?3. ..........complete module survive?

Disentanglement of components!!

• How many beam losses are digestable?• Check for bias voltage dependencies?

• Which component of the components breaks, if any?


Setup

cooling box available (-10°C) (thanks to ATLAS)

2 devices per carrier devices premounted in

carrier incl. patch panel


Carrier

3 ready in KA


Scenario1. Place carrier (DUT) in cold box 2. Full characterization in situ 3. SINGLE 100ns beam spill4. Full characterization in situ5. 2.-4. with different conditions

6. Place new carrier (DUT) ...(3 boxes=times).....etc.

• Full characterization in home lab; hopefully NO failure analysis


3 carriers / tests

1st carrier: HPK-sensor + hybrid (flex) Vbias ramp : one shot per ramp point (0..100V in steps of 20V and 100..400V in 50V-steps)

2nd carrier: ST-sensor + good TEC module

3rd carrier: HPK-sensor + KA prototype TEC module(some pinholes, current..)

after ~30 consecutive beam dumps: detect if the module is still alive!


Parameters on sensors

Readoutstrips

1. Ionisation: completely destroy field configuration/depletion!2. Sensor is short circuited! worst case 400V on CC!!3. Furtunately the power supplies will not react on that time scale!4. Still: Dynamics are complicated and we will try to measure them!

HV: voltage&current!

Voltage over CC: Pinholes?CCbreak>120V(also check for potential on APV)

Single strip current!(also check for Rpoly)

+400V

0V

HV: voltage&current!Single strip current!(also check for Rpoly)Voltage over CC: Pinholes?CCbreak>120V(also check for potential on APV)


Sensor parameterHV: bias voltage Ileak: global leakage currentVAC_DC: Voltage between AC and DC-pads of several groups of strips. 2 or 3 groups are planned!

IDC_biasresistor: also done for 2 or 3 groups of strips Iguard: current possibly induced in the guard ring

= 9 parameters (3 groups) sensors on PCB (circuit discussed with RH)

parameters measured with scopes or FADCs


Strip parametersSingle strip current measurement

Voltage over SiO2 to estimate pinhole development

Scope (measure I)

Scope (measure V)


Test on hybrid (bare and on module)

Parameters:V250: 2.5V hybrid supply voltageI250

V125: 1.25 supply voltageI125

= 4 parameters (measured with scopes)(voltages refer to hybrid ground level)

Readout Standard: APV: Noise, ped, calib


Readout in situ (APV,module)

Use own Karlsruhe CMS-like readout system (good knowledge of the software)

1. Prequalification with normal procedures: pedestal, noise, common mode, calibration, LED,

laser?2. TRIGGER: increase of sensor leakage current

• send APV reset• when APV tickmarks are found:• send software triggers and search for header• monitor baseline behaviour if header is found• Laser response?• LED response

3. Later: full qualification (noise,ped,calib,LED)!


Module parameters

all hybrid parameters HV + Ileak Full readout LED and perhaps laser response

= 6 parameters (measured with scopes)

Reminder: one SINGLE shot full qualification!

Carrier 2&3: Sensor+module will sum up to 30 scope channels!


Readout adventureReadout over 30m of cables!1. Optical readout:

Most promising and probably the only reasonable– Still parts missing– So far NO experience in KA

2. Cat. 7 network cable (needed anyhow for control) (backup 1)

3. PC in the „hot“ area, controlled via LAN (backup2)

Cables have to be installed!Power supply combined effort with ATLAS


Set up of One-shot beamTime required =1.5 days

Conditional on successful replacement of PS power supply and re-establishment of

slow extraction beam line

FIRST 100ns beam extraction ever done at the PS (standard ~ms)

Possible time slots

Duration =8 hours (max)

One shot schedule


Summary• Our electronics plus detectors should be prepared

to survive fast pulses with several orders of magnitude higher particle rates than in nominal conditions.

• We „SHOOT“ a hybrid, 2 modules, 3 sensors with 1011 protons several times varying the bias voltage!

• We are aware that the existing program is very ambitious and the available time is tight, therefore help is welcome!

• Additional ideas/devices like a CCU is feasible, if additional groups join the venture!

• Scopes still needed!• The project is a joint adventure of CMS & ATLAS• The LHCC referee welcomes the project

single shot test beam at ps ! simulation of a beam loss!

Documents