Target Operations

A summary of Target Operation to DatePaul Hodgson

The University of Sheffield

T1 Operation Dates

DAQ Timing Problem

Calibrations Taken

Shift Purpose Date N Pulses

Electronics commissioning From 28-Aug 620

Beamloss/BCD scan 05-Sep 5364

Beamloss/BCD scan plus delay 06-Sep 5819

50 Hz operation tests 08-Sep 1467

Beamline commissioning - 2V BL test 10-Sep 7333

1V beamloss for radiation survey 12-Sep 14644

Beamline commissioning - DAQ debugging 16-Sep 3218

DAQ debugging 23-Sep 459

Beamline commissioning 25-Sep 1129

Beamline commissioning 27-Sep 3465

Beamline commissioning 29-Sep 3818

Beamline commissioning 01-Oct 2549

Beamline commissioning 03-Oct 5859

Beamline commissioning 04-Oct 6833

Beamline commissioning 05-Oct 2150

Beamline commissioning 05-Nov 1920

Beamline commissioning 06-Nov 2822

Beamline commissioning 07-Nov 5630

Beamline commissioning 11-Nov 2178

DAQ commissioning 17-Nov 1906

TOF Calibration 18-Nov 2584

TOF Calibration 02-Dec 2972

TOF Calibration 04-Dec 5946

Emittance Measurements 07-Dec 5590

Emittance Measurements/TOF calibration 10-Dec 5582

Emittance Measurements/TOF calibration 11-Dec 6152

108009

Target Parameters

Start position: x1

Start time: t1

Time beam on: TB1

Time beam off: TB2

BCD minimum: x2

Time BCD minimum: t2

Strike: s = x2 – x1

Strike time: t = t2 – t1

Acceleration: a = 4s/t2

Run reduction code over the raw data to parameterise

Can then plot interesting variables quickly

Interesting Parameters include

Target hold positionTarget BCD – Beam Centre DistanceTarget Acceleration

TB1 TB2

x1

x2

t1 t2

Target Hold Position

1 hour

Takes about 2 hours to warm up

2 populations a result of capture mechanism

Target BCD

Steering target into/out of beam

Stable running

Decreased BCD to increase particle rate

Target Acceleration

Takes about 2 hours to warm up

Rapid change – Ohmic heating of coils

Slower decrease over 2+ hours

Target Acceleration

Takes about 2 hours to warm up

Lots of stopping and starting

BCD HistogramsHistogram BCDs for a set value

Clear difference between the two distributions

Failing target has a much broader spread

T2 distribution 3-4 times as broad

Can be interpreted as a result of the target “sticking”

BCDs for T1 and T2In each case the test runs were setup to pulse with a nominal BCD of 19-20 mm

Very different appearance for BCD time series plots for T1 and T2

T1 very stable BCD does not vary over time

T2 BCD varies strongly over time

Plot very “spiky” after ~42k pulses

Clear signal for target failure

T2 Commissioning Run

Calibration Histograms

Fit double Gaussian to BCD by hand Why ?

Trying to account for second population usually seen

Calibration Histograms

Tricky to automate, usually need to tweak the fit start values by hand to get the fit to converge

Obvious 2nd peak More ambiguous case

Is it better to simply fit a single gaussian or do no fit at all and use RMS ?

Another view of the Calibration

Double Gaussian fitcan pick out second population and gives better resolution for spread

BCD Calibrations to date

All within narrow range ~ 0.6mm

No discernable changeover time

Conclusions

• Have a simple method of spotting potential breakdown of the target

• Target performance looks fine to date• This method is partially automated in current

target DAQ – Thanks James • Still needs an “experts eye”• Don’t want to define some arbitrary failure

value until we see how these measurements evolve