ISOLDE Interlocks MSWG 13 August 2013 K. Hanke, E. Piselli KH

Wrong Beam to ISOLDE certain ISOLDE targets have upper limits for the average and for the bunch intensity different ISOLDE targets require different focal settings and beam steering  in 2009 we introduced a number of interlocks liquid metal target: cracked container welds (sent normal beam instead of staggered) converter target: twisted W convertor rod (sent standard focus with high intensity instead of waist with low intensity) KH

ISOLDE Interlocks Overview watchdog: stop the beam in case of beam loss in the BTY line type of beam (select ‘normal’ or ‘staggered’, others not executed) focal settings: stop the beam in case the settings of the last two quadrupoles before the target deviate from the ones set by the ISOLDE machine supervisor steering: stop the beam in case the settings of the last two steerers before the target deviate from the ones set by the ISOLDE machine supervisor average intensity: stop the beam in case the average beam current exceeds the one set by the ISOLDE machine supervisor (absolute max 2 uA!) intensity per bunch: stop the beam in case the bunch current exceeds the one set by the ISOLDE machine supervisor KH

ISOLDE Watchdog measurement of beam current after PSB recombination and before target interlock condition: difference in beam intensity <300E10 manual reset by the PSB operator needed this is to protect the BTY line from irradiation, not related to ISOLDE itself KH

ISOLDE Beam Types “normal” beam: up to full intensity 4E13 ppp up to 4 rings = 4 bunches used for solid targets, often UC bunch spacing 586 ns users NORMGPS & NORMHRS “staggered” beam: low intensity, depending on target 3 rings = 3 bunches used for liquid metal targets bunch spacing 16 us user STAGISO

ISOLDE Focal Settings on Target ‘standard’ focus up to full intensity steered on target ‘waist’ on target (converter targets) low intensity steered on converter KH

ISOLDE Focal Settings on Target focal settings of the proton beam depend on the type of target they will are set by the ISOLDE machine supervisor after each target change settings must not change any more during that particular run focus interlock condition: setting(device)-2 A ≤ AQN(device) ≤ setting(device)+2 A KH

ISOLDE Steering on Targets steering of the proton beam is done by the ISOLDE machine supervisor for each individual target (proton scan) and settings must not change any more during that particular run position interlock condition: setting(device)-1 A ≤ AQN(device) ≤ setting(device)+1 A KH

Average Proton Intensity (“PPS”) maximum pps value of the proton beam is entered by the ISOLDE machine supervisor for each individual target and settings must not change any more during that particular run pps interlock condition: average 2’(AQN(device)) ≤ MAX PPS absolute maximum value 2 uA except special permission from RP (radiation level of extracted air) KH

Proton Bunch Intensity (“PPP”) 275 300 805 1200 Int.[ppp] t [ms] I(300) maximum ppp value of the proton beam is entered by the ISOLDE machine supervisor for each individual target and settings must not change any more during that particular run ppp interlock condition: I(300)≤ MAX ppp KH

Interlock Actions ppp: cuts RF and comes automatically back as soon as the conditions are OK acts on the cycle which is being executed pps, position, focus: stops beam in the Linac; comes automatically back as soon as the conditions are OK acts on next cycle uses SIS watchdog: manual reset needed KH

Configuration GUI NORMHRS NORMGPS STAGISO waist standard only ISOLDE machine supervisors are authorised to change settings however GUI is not password protected, in principle accessible by everybody from the console manager 12 KH

ISOLDE Vistar displayed in the CCC and ICR KH

Summary In the past there were occasional critical incidents (wrong beam sent, wrong focusing or steering after reloading archives etc.) a number of interlocks have been put in place in 2009 interlocks use standard CERN technology (SIS) since then no more incident interlock conditions change from run to run; the ISOLDE machine supervisor is the only person authorised to manipulate the interlock settings the ISOLDE Vistar has been redone in order to display the relevant parameters in both the CCC and the ICR