140Nd run 1/7 - 4/7 2011

Target issues
* Target number #450 Ta GdB
* Beam on target (no converter). RILIS used.
* Mass markers: Nd, Cs, Sm/Pr
* HRS separator
* Extraction electrode: ?? mm (real distance)
* Uht(HRS, HT_target)=30300 V, Uht(RFQ,CCV)=30208 V, Uht(trap, CCV)=30000 V, Elec05=180 V

Yield measurements
(from Logbook 30/6)

A=140. When protons are off, we believe we do see a laser on/off difference of ca 1-2pa over a total current of ca 4pA.

(from Logbook 3/7)

Users claim they see 6 epA 140A34+ on XL65.FC50. 4 times higher than on Friday. This is for 1.5 uA proton beam, 3E13 ppp. That would correspond to 1.1E6 part/s. 60% of the beam is 140Nd when the lasers are on. On HRS.FC490 I measured 7E-12 pA (for 1.5 uA proton beam). Thus the overall efficiency from HRS.FC490 to XL65.FC50 is 2.5%. On Friday we had a large fraction of the beam, believed to be molecules, lost in the RFQ cooler. This part of the beam is most likely gone now and only atomic beam from the target left.

See also below, delivered beams

Experimental issues
* Beam to Miniball
* IS494

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

ISOLDE
A=138: HRS.FC490=315 pA, Trap inj plate = 248 pA => 79% transmission

Low energy
Stable 138Ba
Tperiod=100 ms, Tbeamgate=10 ms, Tbreed=97 ms (almost optimal), Icoll=188 mA
Trap inj plate 22 pA, RFQ.FC20=56 pA, 29+, trap+EBIS transmission 8.8%

Tperiod=250 ms, Tbeamgate=10 ms, Tbreed=247 ms (not fully optimal)
Trap inj plate 9 pA, RFQ.FC20=14.5 pA, 34+, Trap+EBIS transmission 4.7%. Not splendid.

Radioactive 140Nd34+

Cyclotron frequency 336.4 kHz
Tperiod=251 ms, Tbreeed=248 ms, no beam gate

Linac transmission and energy: 
No stripper foils

Transmission from RFQ.FC20 to XL65.FC50 at 2.83 MeV/u

85%, A/q=4, transmission from RFQ.FC20 to XL65.FC50

68%, A/q=4.1563 133Cs32+, transmission from RFQ.FC20 to XL65.FC50

Total transmission (radioactive beam)
HRS.FC490_to_Trap x Trap_EBIS x Linac
0.75*0.047*0.68=0.024%

Delivered beams

140Nd34+

With 3E13 ppp, 1.4 uA, lasers on. On HRS.FC490<1 pA; on trap inj plate 1.1 pA; RFQ.FC20(34+)=1.9 epA.
We suspect that part of the beam on the trap injection plate is a molecule as the efficiency is so poor. XL65.FC50=1.3 pA. Miniball FC with an empty frame 1 epA. We have 1.3 epA*/(1.6e-19*34) =240000 particles/s. Agrees with yield tests.

Setting summary
For HRS we used:

* HRS_SEP_2011-06-29_30kV_138Ba.csv
* RFQ_2011-06-29_30kV_138Ba.csv

* REX_RFQ_2011_06_29_138Ba_30Kv.csv

REX low energy settings saved as:

* 110629_0839_TRAP_133Cs_HRS.csv

* 110630_1554_BTS_138Ba_HRS.csv

* EBIS_110701_0940_HRS_138Ba34_4.7%.csv

REX separator and linac settings saved as:
* 110701_1156_SEP_Aq4.1176_140Nd34_MB.csv
* 110701_1156_Aq4.1176_140Nd34_MB.csv 

Technical problems

· XL20-65.MQ10 didn’t go higher than 132 A, would have liked 150 A. Cooling problems.  

· REXTRAP RF problem during the setup. Readout of XBTS.FC20 stopped working.

· BTS-line elements stopped, reason unknown. Beam back to the users after 10-15 min stop.

Comments / Lessons learned

· Large fraction of the A=140 beam made up of molecules. Thus only 10% transmission through the RFQ cooler.