9C run June 2010

Target issues

* Target number #425 YO VD7 + coldline (Cu)

* Beam on target (no converter)

* Mass markers: enriched 13CO gas (was not necessary: enough current from natural abundance)

* GPSseparator

* Extraction electrode 40 mm

* Uht(GPS,CCV)=29.95 kV, Uht(GPS, HT_target)=29.9612 kV, Uht(trap)=30.00kV, Elec05=220 V

Yield measurements

From the logbook:

* Wed 9/6

ca 1.5e3/muC estimated 9C yields, on top 2/3 (in betas) 25Ne contamination

* Fri 11/6

25Ne : ca 2.5e4/muC

26Ne : ca 2.8e3/muC

72Kr : ca 4e3/muC

Could not get 9C again.

Experimental issues

* Beam to 2nd beamline

* IS445

Tuning

* Molecular beam CO

* REXTRAP timing free-running relative to protons pulses

* use of stripping foils (25 ug/cm2) to go from C4+ to C6+

ISOLDE

Transmission A=29: GPS.FC490=2.67 nA, Trap inj plate 2.07 nA => 77%

Low energy

Stable beam 13CO

Tperiod=20 ms, Tbreed=8 ms (optimised for 4+), Icoll~110 mA, molecule broke-up inside the EBIS
Trap inj plate=55 pA, RFQ.FC20=13 pA (4+) =>Trap-EBIS efficiency=6% efficiency

Radioactive 9C

No currents measured anywhere.

Linac transmission and energy:

85% RFQ.FC20 to XL20.FC50 for A/q 4, 2.87 MeV/u

82% RFQ.FC20 to XL20.FC50 for O7+ A/q 2.2857, 2.87 MeV/u

50-68% RFQ.FC20 to exp FC for O7+ A/q 2.2857, 2.87 MeV/u (3 mm colimator in front of set-up)

Total estimated transmission (radioactive beam)

GPS x Trap_EBIS x Linac_collimator

0.77 * 0.06 * 0.60 = 2.7%

Delivered beams

* 9C: very low count rate at exp (-> run cancelled)

From logbook Thu 10/6:

Beam composition from last night data:

* >500 pps from EBIS most likely 18O

* 50 pps from GPS maybe 9Be coming as BeO (cannot be 25Mg -> too heavy)

* small contribution from 4He (could be beam created at the wrong potential in the EBIS)

Setting summary

ISOLDE settings saved as:

GPS_SEP_10-06-04_Ar_30250V.csv

GPS_REX_10-06-09_HT29950V_plasma160V_A29.csv

REX settings saved as:

REX-30kV_2010-06-09_GPS_9C16O_flatpotential.xml

BTS-30kV_2010-06-07_GPS_13C16O_flatpotential.xml

EBIS_100609_1900_GPS_9C16O_9C4.csv

100609_1902_SEP_Aq2.25_9c4+_2.87MeVu_set-up_no-foil.csv

100609_1902_Aq2.25_9c4+_2.87MeVu_set-up_no-foil.csv

Technical problems

* Problems with EBIS cathode, had to run with injected O2 to maintain enough electron beam current

* FC communication problem most of the set-up time was used to debug control system

* charging-up problem in connection with scaling at low A/q

Comments / Lessons learned

* Linac can be run at very low amplitude A/q=2.25

* Not enough time to set-up higher energy, would be interesting to see what energy can be reached with such light beams