Operational aspects 2008 run ISCOOL Isolde workshop Nov 2008 Erwin Siesling

Isolde workshop 08: ISCOOL OP aspects E. Siesling 2 Overview ISCOOL: RFQ cooler and buncher at Isolde Hardware Functionality, principle and specs Technical issues 2007/2008 Results 2008 run Shutdown consolidation Summary

Isolde workshop 08: ISCOOL OP aspects E. Siesling 3 ISCOOL hardware Inj. Triplet Ej. Triplet RFQ tank Instrum. 60 kV

Isolde workshop 08: ISCOOL OP aspects E. Siesling 4 ISCOOL hardware

Isolde workshop 08: ISCOOL OP aspects E. Siesling 5 HRS GPS Located right after the HRS separator magnets RFQ Cooler and buncher ISCOOL hardware Isolde facility

Isolde workshop 08: ISCOOL OP aspects E. Siesling 6 60keV HV platform & RF ISCOOL hardware Isolde facility

Isolde workshop 08: ISCOOL OP aspects E. Siesling 7 ISCOOL functionality RFQ: Confines the beam and reduces energy spread for better transmission and higher mass spectroscopy efficiency Bunch mode: Bunches the beam for background supression Continuous mode & Bunch mode

Isolde workshop 08: ISCOOL OP aspects E. Siesling 8 Courtesy Dr. H. Franberg ISCOOL principle He buffer-gas: Interactions decelerate the particles to a few eV RF power: 4 transverse rods. Confines the beam Mathieu equation Electrodes: Potentials along the axis. 3 last and extraction plate can be pulsed HV extraction voltage: 60kV to extract and accelerate the beam out of the RFQ RFQ RF Bunch mode

Isolde workshop 08: ISCOOL OP aspects E. Siesling 9 Emittance: Transmission: Cooling time: Space charge: Pulse width: ISCOOL specs from 35π.mm.mrad to 2.2 π.mm.mrad better than 70% for A>39 TOF <1ms, one passage enough to cool the beam up to 1E8/s ! depends on space charge and cooling time

Isolde workshop 08: ISCOOL OP aspects E. Siesling 10 The ISCOOL has been performing remarkably well during the 2008 run with only a few minor technical problems 2007/8 shutdown consolidation: - elements controllable from RFQ workingset & QP array - vacuum leaks fixed & interconnections improved - re-aligned 2008 operation issues: - Excessive use of He buffer gas - RF amplifier break down (due to abrupt HV switching) ISCOOL tech issues

Isolde workshop 08: ISCOOL OP aspects E. Siesling 11 Workingset for all elements 2007/8 consolidation QP arrays: Archive to save and reproduce settings for different targets and users

Isolde workshop 08: ISCOOL OP aspects E. Siesling /8 consolidation Vacuum leaks repaired & connections improved

Isolde workshop 08: ISCOOL OP aspects E. Siesling /8 consolidation Re-alignment: ? Aligned with respect to the faraday-cups: displacement of the beam with regard to the scanners of hor -10mm, vert +30mm stayed With beam..

Isolde workshop 08: ISCOOL OP aspects E. Siesling Operation issues He Buffergas pressure: ~1E-2 mbar 4 He Estimated: mbar l/s But… Helium ‘addiction’: -Using 3x more -Bottle needs changing ~6 weeks -Filling-up Isolde gas-recuperation tanks faster He buffergas

Isolde workshop 08: ISCOOL OP aspects E. Siesling Operation issues RF amplifier & synthesizer High Voltage sensitive: - Break down due to abrupt HV switching - Will be replaced this shutdown (+ spare) 60kV

Isolde workshop 08: ISCOOL OP aspects E. Siesling 16 ISCOOL 2008 results ISCOOL transmission Beamline transmission Bunch mode

Isolde workshop 08: ISCOOL OP aspects E. Siesling 17 Inj. Triplet Ej. Triplet RFQ tank Instrum. ISCOOL online transmission Courtesy Dr. H. Franberg Sources Modes ISCOOL transmission >70% for A>39: - In general between 70-80% for plasma targets, somewhat higher for surface ion sources. Depends on the emittance coming from the ion source - In pulsed mode some higher losses related to the trapping time

Isolde workshop 08: ISCOOL OP aspects E. Siesling 18 Beamline transmission HRS GPS Merging switchyard losses 50-70% ISCOOL ~35π.mm.mrad ~2π.mm.mrad Higher mass spectroscopy efficiency 100% transmission Beamline transmission: - low emittance beam after the cooler is easily tuned to the different experiments with a transmission efficiency of up to 100%

Isolde workshop 08: ISCOOL OP aspects E. Siesling 19 Bunch mode ISCOOL in bunch mode Collaps HRS Background suppression of factor ~1E4 by gating on the beam pulse 46K beam 1E5 ions/s after the cooler. Collection time 20 min, with 300ms bunching, 12us gate and 2mW laser power Ernesto Mane: ‘First results using the ISCOOL-COLLAPS apparatus’

Isolde workshop 08: ISCOOL OP aspects E. Siesling 20 Bunch mode ISCOOL in bunch mode REXtrap HRS ISCOOL gated by trap timing (10 units = 20us) 20uS New 'tricks' for REX injection: - Mass purification at REXtrap using RF excitation. - Direct pulsed injection into EBIS without use of the trap: The space- charge of the RFQ bunches is much higher than what can be achieved with the trap. Acceptance of EBIS would be large enough and it would increase beam intensity to the linac. Anna Gustafsson: ‘The REX low-energy toolbox’

Isolde workshop 08: ISCOOL OP aspects E. Siesling /9 shutdown consolidation: - vacuum controls (Julien de Freitas) - new RF amplifier (Pascal Fernier) - MCP re-installed? 2008/9 shutdown

Isolde workshop 08: ISCOOL OP aspects E. Siesling 22 Reliable 2008 performance with very few issues - RF amplifier will be replaced + spare - Vacuum will be integrated in the Isolde controls ISCOOL transmission 70-80% depending on mass and ion source Easy tuning and beamline transmission improved to 100% Bunch mode working well with future potential: - background suppression - mass purification at REX TRAP - direct injection in to REX EBIS Details in the 2008 ISCOOL performance report by Dr. H. Franberg, Dr. Pierre Delahaye, et al. ISCOOL webpage: Summary

Isolde workshop 08: ISCOOL OP aspects E. Siesling 23 Special thanks to Hanna, Pierre and Tim The Isolde OP-team, AB/OP-PSB-iso AB/ATB, AB/VAC, AB/PO, AB/CO and Alexandre Dorsival (SC/RP) for making the ISCOOL 2008 run a success Thanks