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LHC BI 2015 Summary: BSRLM. Palm (BE-BI-PM)

2015-11-12

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Changes since Run 1Optical line• BSRL and BSRA on

extension table

Hybrid detectors installed• Both beams since TS2

TS3• Hybrid shutter control

installed• Additional layer of protection

against saturation

2015-11-12

APD

• IRF widens at shorter wavelengths

•Filter Better signal at high energies

Color filter (APD)

Synchrotron light

•Fiber-coupled sub-ns pulsed laser installed in gallery

•SPAD afterpulse calibration

•System functionality verification

Pulsed laser

• Reduce impact (signal variation) of extraction mirror movement

Diffuser (APD)

•Replacing filter wheels

•5 filters (Attenuation up to ~107)

Neutral density filters

BSRA

•Block reflections

Screens

Hybrid

APD: Performance

2015-11-12 3

Distorted bunch profile

“Phantom” bunches

“Phantom” bunch signal typically decreases

during the fill

Mechanism not fully understood…•Possible cause: bias voltage ripple (>GHz) leading to sensitivity fluctuations and avalanche onset.

Hybrid: Intended use (1)

2015-11-12 4

Doublets

Satellites

Doublet train, B1 (Fill 4164)

Satellite fraction (

Ghost fraction (

vdM-scan: Ghost & Satellite fraction

Hybrid significantly

better than APD

Flattop

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Hybrid: Intended use (2)

2015-11-12

B1 Satellite & Ghost map (vdM scan, Aug 25)

=Filled/masked bucketAbort Gap

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Hybrid: Bonus

2015-11-12

Abort gap population Synchronous phase shift, Bunch by bunch

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(No baseline subtraction)

RawBeam loss correction

Hybrid: Unexpected

• Most likely beam losses(?)

• Bunched signal from wrong beam corrupts measurement

• …can be corrected• Long term damage?

Profile of opposite beam is detected

2015-11-12

B1 structure seen by B2 hybrid

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Outlook

• Install BSRL equipment on removable breadboard

YETS

• Investigate BSRL installation in UA• Less exposed to radiation• Two complementary systems in RA

and UA• Issues:

• Broad-band light signal through 75 m fibre => Severe dispersion

• 2’’ light cone into ~10s m fibre• Scintillation?

2016

2015-11-12

Current location

New location?

Fibre

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Backup

2015-11-12

Hybrid abort gap estimate and measured beam loss