machine-detector interface (mdi) report

M. Weaver PEP-II MAC Review,15-17 Nov’07

Operational issuesOperational issues radiation aborts

background monitoring

Background extrapolationsBackground extrapolations model comparisons to performance

simulations

vulnerabilities

IP characterization measurementsIP characterization measurements

Machine-Detector Interface (MDI) reportMachine-Detector Interface (MDI) report

Presented by M. Weaver, SLAC


Run-6 radiation-abort historyRun-6 radiation-abort historyB. Petersen

S. Curry

<stable-beam trips> ~ 2.8/day

Jan2007

May2007

Sep2007

Jul2007

Mar2007


ForwardWest

ForwardEast

BackwardWest

BackwardEast

Abort-by-dose locationAbort-by-dose location

HER vacuum events

Jan2007

May2007

Sep2007

Jul2007

Mar2007

Jan2007

May2007

Sep2007

Jul2007

Mar2007


Background Monitoring SummaryBackground Monitoring Summary

SVTRAD diodes + diamondsSVTRAD diodes + diamonds dose rates, dose / injectiondose rates, dose / injection

DCH high voltageDCH high voltage currentcurrent

DRC PMTsDRC PMTs scaler ratesscaler rates

IFR high voltageIFR high voltage currentcurrent

Fast Control & TimingFast Control & Timing deadtime, L1 rates, deadtime, L1 rates, time wrt injectiontime wrt injection

Level 3 TriggerLevel 3 Trigger subdetector occupanciessubdetector occupancies

Neutron counters Neutron counters scaler ratesscaler rates

CsI IP detectorsCsI IP detectors (logarithmic response)(logarithmic response)

All update in small intervals (1-5 seconds)All update in small intervals (1-5 seconds)


Run-6 radiation-dose ratesRun-6 radiation-dose ratesD

ose

rate

(m

rad

/s)

Pre

ssu

re (

nT

)

Incoming HERVacuum

BW DiamondBE Diamond

Incoming LERVacuum


Injection- & trickle- background historyInjection- & trickle- background history

Monitor by integrating SVTRAD diode signals over 12 ms after each injection

SVT electronics are sometimes “upset” by exposures greater than 50 mrad / injection.

HER injection-quality monitor

LERLER injection-quality monitor

Ave

rage

Dos

e/In

ject

ion

(m

rad

)

Ave

rage

Dos

e/In

ject

ion

(m

rad

)


DIRC PMT Scaler RateDIRC PMT Scaler Rate

DIRC reconstruction has been shown to be robust up to 1MHz

hit rate.


Detector Occupancies (%)Detector Occupancies (%)S

VT

Lay

er 1

Eas

t

SV

T L

ayer

1 W

est

DC

H T

otal

EM

C T

otal

Tuned noise thresholds and tightened time

windows


Background sources in PBackground sources in PEEP-IIP-II

Beam-gas (bremsstrahlung + Coulomb)Beam-gas (bremsstrahlung + Coulomb)

HEB only: BHbg ~ IH * (pH0 + PH

Dyn * IH) Note: p0 = f(T) !

LEB only: BLbg ~ IL * (pL0 + PL

Dyn * IL) Note: p0 = f(T) !

beam-gas x- term: BLHbg ~ cLH * IL * IH (LEB+HEB, out of collision) (?)

Luminosity (radiative-Bhabha debris) – Luminosity (radiative-Bhabha debris) – major concern as L major concern as L BP ~ dP * L (strictly linear with L)

Beam-beam tailsBeam-beam tails

from LER tails: BL, bb ~ IL * fL(L,H +/-)

from HER tails: BH, bb ~ IH * fH(L,H +/-)

Trickle background: BTrickle background: BLi Li ,, BBHiHi (injected-beam quality/orbit + beam-beam)

Touschek: BTouschek: BLTLT (signature somewhat similar to bremstrahlung; so far small)Still using characterization of Jan’04


Projected DAQ Requirements/PerformanceProjected DAQ Requirements/PerformanceP

roce

ssin

g T

ime

Fiber TransferFeature Extraction

Pro

cess

ing

Tim

eThreshold tuning

and window tightening

upgraded

upgraded

L1

Rat

e (H

z)

Time

7.0kHz “ceiling”

5.8kHz average

upgraded


SVTSVT Integrated dose will be more than 1 Mrad/year

Backward:

Forward:

TopEast West Bottom

TopEast West Bottom

NO

W20

0420

0520

0620

07

Background will be 50% HER, 50% L

Background strongly - dependent

Predict 80% chip occupancy right in

MID-plane

In layer 1, 10% will be above 20% occupancy

Projected Detector OccupanciesProjected Detector Occupancies


Background model comparisonsBackground model comparisons(measured/model)(measured/model)

Bwd East Dose Rate Bwd West Dose Rate

Lots of vacuum work during pre-Run6 downtime resulted in a long

time to scrub.

HER vacuum performance still better than

predictions from Jan’04 characterization.

Rat

io


DCH Background L1 Trigger Rate


Trigger rate somewhat larger than characterization. Results in higher

deadtime.

Run6 backgrounds still consistent with characterization.


DRC Background


Large fluctuations but tolerable

in this subdetector.


Machine Background SimulationsMachine Background Simulations

Long effort to simulate sources of machine backgrounds to Long effort to simulate sources of machine backgrounds to improve understandingimprove understanding

Added interest from future B-factory designersAdded interest from future B-factory designers

Difficulty integrating toolsDifficulty integrating tools

LER model was completed long ago and simulated with not-LER model was completed long ago and simulated with not-so-satisfactory results. Problems uncovered generating so-satisfactory results. Problems uncovered generating HER model. At long last, HER model is consistent among HER model. At long last, HER model is consistent among the tools. Ready to simulate and analyse.the tools. Ready to simulate and analyse.

Analysis may learn something in time to compare against Analysis may learn something in time to compare against machine operation but benefit is unknown.machine operation but benefit is unknown.

AcceleratorDesign(MAD)

PrimaryInteractions

(Turtle)

Secondary Interactions+ Detector Response

(GEANT)


Detector VulnerabilitiesDetector Vulnerabilities

Readout DeadtimeReadout Deadtime

Inefficiencies, backgrounds (combinatorics)Inefficiencies, backgrounds (combinatorics)

DamageDamage

SVT

Total

DCH

EMT

Extrapolation (5.8kHz)

x2 Background (7kHz)

BaBar experts are estimating worst tolerable conditions

A tightened “emergency” A tightened “emergency” trigger configuration is trigger configuration is ready, just in case…ready, just in case…


IP CharacterizationIP Characterization

Use BaBar’s tracking resolution and prime venue for Use BaBar’s tracking resolution and prime venue for measuring important parameters at the IPmeasuring important parameters at the IP

Three analyses each measuring y, *y

dLumi / dz vertexing e+e- and +- events

yLumi(z) +- events

y’Lumi(z) +- events

(resolution)Production vertices (x,y,z ~ 30m)

Boost trajectories ( ~ 0.6 mrad)

e- beam

e+ beam


BaBar IP measurements reported onlineBaBar IP measurements reported online

Luminous RegionLuminous Region centroids { x, y, z}

sizes { x, z } every 10 minutes

tilts { dx/dz, dy/dz }

dL/dz fit { z, *y, zw, zc} every ~hour

Boost TrajectoryBoost Trajectory mean { x’, y’ } every 10 minutes

spread { x’HER, y’HER } every 30 minutes

}


VRF

z (

mm

)

Bunch Length Extraction from dBunch Length Extraction from dLL/dz Fits/dz Fits

BaBar Run

z2 = 10.3 mm2 ± 0.4 mm2

z H ,10.9 mm10.4 mm

10.8 mm ± 0.2 mmz L ,

± 0.2 mm

y* = 13mm


dL /dz

IP Beta Function Measurements

yL

y’B

PEPphase

advance2


Summary (I)Summary (I)

Expect a painful scrubbing process at the beginning of Run7.Expect a painful scrubbing process at the beginning of Run7.Lots of HER arc vacuum work done to remedy source ofLots of HER arc vacuum work done to remedy source ofabort-inducing vacuum events.abort-inducing vacuum events.

Injection backgrounds sometimes problematic but generally Injection backgrounds sometimes problematic but generally under-control under-control

Stored-beam bgds (dose rate, data quality, dead time) Stored-beam bgds (dose rate, data quality, dead time) Some differences from run5 but similar magnitude. No new thermal outgassing/vacuum activity near the detector.

Background characterizationBackground characterization No new experiments. Too late in the game to repeat, no time

for hardware interventions. Latest measures of the projected backgrounds still look good. Uncertain about beam-beam backgrounds – Run5 experiment

suggested not so large, Run6 experience somewhat different.


Summary (II)Summary (II)

SimulationSimulation After a long struggle, ready to analyze HER backgrounds.

BaBar-based IP characterizationBaBar-based IP characterization Incorporating effects of coupling

Working on including X-ray and SL beam profile monitors


Spare SlidesSpare Slides

machine-detector interface (mdi) report

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