26,30Na run 24-29 August 2011

Target issues
* Target number #457 UC W-surf
* Beam on target (no converter)
* Mass markers: Na, Mn, Rb
* GPS separator
* Extraction electrode 69 mm (real distance)
* Uht(GPS, CCV)=30.20 kV, Uht(trap, CCV)=30000 V, Elec05=190 V

Yield measurements (from logbook):

23/8 Preliminary yield of 30-Na from measurements at old tape station (using the decay daughter 30-Mg and assuming 100% decay into 30-Mg):

target/line at 1800C/2000C: 1e3 ions/uC (decreasing tendency in time)

target line at 2000C/2000C: 3e3 ions/uC

24/8 Lowering target and line to 1800/200C: Target to 571A, Line 286A.

Yield between 1 - 6E3 ions/uC

Experimental issues
* Beam to Miniball
* IS482

Tuning
* Normal extraction from EBIS 
* REXTRAP timing free-running relative to protons pulses

* Na too unstable to tune on, used Al

ISOLDE
For 27Al transmission from GPS.FC490 to TRAP.FC10: 71%.

Low energy
Stable beam 27Al

Tperiod=21 ms, no beam gate.

Trap inj plate=44 pA, BTS.FC20=27 pA, mostly 27Al in the peak. Transmission=61%

TRAP HT=30000 V, Trap gas=7.5 V, Cyclotron frequency 1692 kHz

(Using freestanding RF generator as the CVORG gave to big jitter)

With Tperiod=21 ms and Tbreed=18 ms (optimised breeding time for 8+) e-coll 167 mA

=> TRAP+EBIS efficiency 12.5%

Linac transmission and energy: 
No stripper foils. WITCH magnets 0.1 and 3 T.

Transmission from RFQ.FC20 to XL65.FC50

- 84% for cocktail A/q = 4 at 2.82 MeV/u

- 66% for 133Cs31+ A/q=4.2903 at 2.85 MeV/u

Reduced the 9-gap amplitude and retuned the phase to run with less power out of the amplifier (power limited to 80 kW following amplifier problems).

Total transmission (radioactive beam)
HRS.FC490_to_trap x Trap_EBIS x Linac
0.71*0.125*0.80=7.1%

Delivered beams

30Na7+ @ 2.82 MeV/u (from Wed 24/8 night to Thu morning)

Cyclotron freq. 1522823Hz, Period time 20ms, breeding 15ms, Tinj 60us

Miniball estimate: 40 ions / s for 1 uA on target

We measured the Na beam intensity twice:

(i) Collection at MB target and beta decay measurement (at 1.0uA protons)

-> This gives the 41 ions/sec quoted in the logbook.

(ii) Elastic scattering into CD (at 1.9uA protons)

-> This gives roughly 80-100 ions/sec which is in agreement with the one

from beta-decay. Michael Seidlitz

Estimate was between 1000-6000 ions/uC from the target (Alex Gottberg)

Due to the quick target degradation these figures can/are be consistent.

26Na6+ @ 2.82 MeV/u (from Thu 25/8 mid-day to Mon morning)

With 3E13 ppp we see 0.8 pA in the peak on trap inj plate

RFQ.FC20=0.6 epA => 12.5% efficiency for the low energy stage

Period time 20 ms, breeding time 12 ms

Setting summary
GPS settings saved as:

GPS_SEP_30kV_#457_2011-08-22-39K.csv

GPS_TAP_30kV_#457_2011-08-22-39K.csv

REX low energy settings saved as:

110824_1542_TRAP_30Na_7+_GPS

110824_1542_BTS_30Na_7+_GPS

EBIS_110824_1544_GPS_30Na7+

REX separator and linac settings saved as:
110824_1540_SEP_Aq4.286_2.82MeVu_L65_30Na7+_MB

110824_1540_Aq4.286_2.82MeVu_L65_30Na7+_MB

Technical problems

* We ran with freestanding RF generator for the REXTRAP as the CVORG gave to big jitter.

‘In the Scope-in-a-box I see a jitter for +-10 ns between the RF channels. For light masses where the cyclotron frequency is >1.5 MHz, this corresponds to +-1.5% phase jitter. The jitter is equal to a dipolar excitation, which might not be insignificant for +-10 deg. /FW
* Turbo pump IHS11 stopped without obvious reason. Beam off for ~2 h.

Comments / Lessons learned

* Tuned on 39K8+ (A/q=4.333) instead of 133Cs31+ (A/q=4.2903) from local ion source.

NEVER GO MORE THAN 0.03mT OFF FROM THE THEORETICAL VALUE FOR SEP.MD100: ASK YOURSELF 'WHY' IF THIS GIVES YOU MORE BEAM!