Experimental tests of HIE-ISOLDE beam instrumentation

Beam diagnostics in the beamlinesSergey SadovichCERN BE-BI-PM

on behalf of BE-BI-PM

OutlineHIE-ISOLDE diagnostic system overviewShort and long diagnostic boxesInstruments and devices

Faraday CupScanning slitCollimator and stripping foilsSilicon detector2Diagnostic boxes:3

Possibilities:Beam current measurementProfile and position measurementBeam emittanceEnergy of beam measurementStripping foils4Types of DB:5

Short and Long diagnostic boxesDue to tight space constraints in the longitudinal direction, two designs for the DBs were implemented:Linac: Short DBs (5).HEBT: Long DBs (8).

The functionality and operation of the instruments is similar in the SDBs and LDBs. The only difference between them is that the SDBs have a compact Faraday cup.

Depending on which devices are included on each DB, there can be up to 4 different types/configurations of DBs.

scanning slitstripping foilsFCSi. detcollimatorsvacuum portbeam

short FClong FC6Instruments summary7InstrumentInputsOutputsPlane *PositionsConnected toFaraday cupV repellerI signal plate2IN OUTFC preamplifier +VME boardScanning slit1continuous stroke 135 mmSi detectorHVparticle energy and time of arrival2IN OUTand continuous adjustmentpreamplifier + VME digitizer V1724Collimators 114 setpointsand continuous adjustmentCollimators 214 setpointsand continuous adjustmentStripping foils13 setpointsand continuous adjustmentFaraday Cup8

-67 V

IbeamIFCVrepDesign for short FC

FC working zone

IbeamIFCVrepFinal design

Faraday Cup9A blade with a V-shaped slit is scanned upstream the FC.Vertical and horizontal profiles are acquired, and the beam position is calculated from them.A 1 mm collimator hole is also included in the blade and can be used for beam alignment. The position of the blade needs to be controlled for the full stroke (135 mm). The actuator is driven by a stepper motor.

DetectorBeam

10Scanning slit10

Transverse profile: scanning slit + FC

Horizontal and vertical profiles.Beam size and position.11

Transverse emittance: 2 slits + FCMonteCarlo simulation of particles transport

optimal slit width w = 1 mmcan be implemented with2 DBs at the HEBT (d = 2.6 m)

12Scanning slit: position measurement13

Collimators and stripping foils14

Preset positions (1 to 4, or OUT) or arbitrary value.Actuator driven by a stepper motor.

Collimators: position measurement15

Silicon detector

preamplifiercharged particles spectroscopytime of flightenergy chaintiming chainTotal particle energyMass compositionParticle speedBunch length

energy spectrumTOF spectrumDetector bias (60 or 100 V) supplied through the preamplifier.Preamplifier power: 24 V, 12 V provided by shaper amplifier.Leakage current monitoring can be used to determine detector aging and also to block the beam if dose rate is too high.Requires the time signal for the RF master-oscillator and the EBIS pulse for triggering the TDC and gating the acquisition.Integration time controlled by the user.Works at an average rate of ~100s particles per second. Beam intensity needs to be severely reduced placing collimating foils in DB2 and DB3. 1616Implementation:

Canberra 2003BTThe output provides a voltage in direct proportion to the collected charge at the rate of 0.45 V per pC. This translates to a gain of 20 mV per MeV for room temperature silicon detectors.

CAEN V1724 with DPP-PHAVME module with8Channels14bit100 MS/sFlash ADC Waveform Digitizer and featuring 10 Vpp input dynamics

0-10V /20 mV = 0-500 MeV500 MeV / 2^14 = 30.5 keV per bitCanberra PIPS detector(TM)PD50-11-300AM50 mm2

Resolution 11(16) keV FWHM for 241Am, 5.486 MeV alphas17SummaryDBs in tunnel are installedDBs for XT01 line are installedDBs for XT02 line are ready to be installed

Stripping foils have to be installedSilicon detectors for SDB5 and LDB6 have to be installed

Following measurements can be performedBeam intensity: Faraday cup (+ collimators).Setting up the accelerator and aligning and transporting the beam.Beam transverse profiles (and position): Scanning slit + FC.Horizontal and vertical profiles.Beam longitudinal profile: Silicon detectors.Energy and time spectra.Time of flight measurementsTransverse emittance: 2 scanning slits + FC Stripping foils.