1. Possible new EMMA injectors bdm

2. Motivation ALICE due to shut down soon Alternate EMMA injection (assuming EMMA project continues which it should …) Several options – Carry on using first part of ALICE – Entirely new injector Gun – SRS / NINA thermionic gun Booster – SRS 3 GHz travelling wave linac Injection line – use existing ? – Any combination of the above Other injector / gun ? 2

3. EMMA Requirements 3 (this is more like 20-60 pC during EMMA operation) (< 20 keV but the smaller the better)

4. Injection line ALICE ? EMMA SRS 12 MeV Linac SRS quadrupoles Quadrupoles Thermionic gun Screen SRS layout Possible new layout 4

5. SRS / NINA gun Thermionic electron triode gun & solenoid 80 kV & ~ 12 new cathodes exist Peak beam intensity ~ 0.350 A (0.6 A maximum) Achieved parameters are almost comparable to present ALICE apart from – Bunch length - typically ~ 1 ns maybe slightly less for ~ 0.4 nC total charge hard for the EMMA kickers – Intensity very low as a result of chopping But there is not much room for manoeuvre and change any of the parameters easily if this should be desired / required 5

6. SRS / NINA gun 6

7. SRS linac Buncher has been tried → multipacting Choppers after → loss of intensity Linac in three sections but no control or field map Courtesy A. Moss 7

8. SRS linac Plenty of solenoids exist Provides independent focusing in both linac sections Only have RF power & phase for entire linac as parameters plus two focusing solenoids gun bucking solenoidvalve I 0 coil solenoid # 1 solenoid # 2 linac I b coil bunching section solenoid accelerating section solenoid 8

9. Energy spread Energy spread +/- 0.5 % which is ~ok for EMMA but at the moment we have achieved ~ 0.05 % ALICE & playing with linac phases can do better 9

10. Possible NC Layout (1) Can optimise for – Bunch length / emittance (x, y, z) / energy pread and output parameters at exit 10

11. NC booster cavity(ies) Possible NC Layout (2) One NC cavity useful but 2 would be better for minimizing the energy spread (phase freeedom)

12. Possible NC Layout (3) 12 Bunch length Beam size (x & y) Emittance (x & y) Energy Spread Emittance (z) Performance comparison of old (ALICE) set-up & new suggested NC set-up

13. Possible NC Layout (4) Parameters worse than present ALICE ones – this is important as there shall be no further cavities to rectify things like energy spread However, it is an acceptable solution for EMMA 13

14. Conclusions / Observations A lot of components missing for SRS set-up (e.g.) – Power supplies for gun – Modulator for linac No field map for linac → modelling difficult but maybe not impossible Lack of independent control of three linac sections → difficult to adjust / operate Linac only just provides required energy spread when at best Separate NC option not optimal either due to lack of control of beam parameters 14

15. Conclusions / Observations A lot of beam was wasted during operation of this gun & linac due to a lack of focusing – could this be improved ? If yes, could possible charge be up to 4 nC over 1 ns which is good for EMMA ? Could we use an alternative gun / linac from elsewhere ? Can we find an off the shelf medical linac we could use ? Could we use a microtron ? Any other suggestions ? 15

16. Possibilities (1) Rob Edgecock

17. Possibilities (2) Peter McIntosh 2002 prices