ENDTOEND SIMULATIONS OF LINAC 4 Introduction Layout Linac

END-TO-END SIMULATIONS OF LINAC 4 Introduction Layout Linac 4 is a new H- linear accelerator that will replace Linac 2 and will provide the conditions to double the brightness and intensity of the beam delivered to the PS Booster. This machine consists of normal-conducting structures operating at 352. 2 MHz It consists of a 45 ke. V H- source, an RFQ bringing the energy to 3 Me. V, a Chopper line, a Drift Tube Linac bringing the energy to 50 Me. V, a Coupled Cavity Drift Tube Linac bringing the energy to 102 Me. V and a PI Mode Structure accelerating the beam to 160 Me. V to inject in the PS Booster. Each section is designed and optimized as stand-alone machines for a good transmission and minimum emittance growth. End-to-end simulations starting from the source have been carried out in order perform a global optimization of the structures in the context of a complex machine. 45 ke. V 3 Me. V 50 Me. V 102 Me. V 160 Me. V H- LEBT RFQ MEBT DTL CCDTL PIMS RF Volume source + postacc Low Energy beam transport 2 solenoid Radio Frequency Quad. MEBT 11 Quads 3 Cavities 2 Chopper units. Drift Tube Linac 3 Tanks 114 PMQ 1 EMQ Π-mode Structure 12 Modules 12 Quads 1. 9 m 1. 8 m 352. 2 MHz 3. 9 m 352. 2 MHz 19 m Cell-Coupled Drift Tube Linac 7 Modules 21 Tanks 21 Quads 352. 2 MHz 25 m 352. 2 MHz 22. 9 m Beam dynamics The LEBT Losses Input beam β εrms ε 90% x -6. 64 0. 36 mm/ π mrad 0. 25 π mm mrad 0. 90 π mm mrad y -6. 64 0. 36 mm/ π mrad 0. 25 π mm mrad 0. 90 π mm mrad z 0. 0036 356086. 45 deg/ π Me. V 0. 03 π deg Me. V 0. 11 π deg Me. V RMS normalized emittances α RMS beam size The losses are mainly in the RFQ (6. 7%) and the Chopper. The total transmission when the chopper is OFF is ~96%. The LEBT has been simulated only with Path Manager. The RFQ has been simulated with Toutatis and PARMTEQM. From the Chopper to the PIMS, each machine has been simulated both with Path. Manager and Tracewin. (Only Path. Manager results are plotted) The Twiss parameters of the input beam (at the output of the source ) are reported in the following table. Losses in the LINAC, Chopper OFF Output beam The PIMS output beam has the Twiss parameters reported in the following table (Path. Manager values). α β εrms ε 90% x 1. 77 5. 56 mm/ π mrad 0. 30 π mm mrad 1. 26 π mm mrad y -2. 95 10. 79 mm/ π mrad 0. 30 π mm mrad 1. 25 π mm mrad z 0. 13 22. 28 deg/ π Me. V 0. 16 π deg Me. V 0. 65 π deg Me. V Losses in the Chopper line The DTL The Chopper Line The CCDTL The PIMS RMS beam size DUMP RMS normalized emittances DUMP Energy Cavity Settings Emittance growth PIMS MEBT CCDTL DTL CCDTL PIMS Quadrupole Settings DTL MEBT DTL CCDTL PIMS εx, rms εy, rms εz, rms εx, 90% εy, 90% εz 90% LEBT 8. 16 % 8. 37 % - 18. 56 % 18. 86 % - RFQ -9. 96 % -10. 3 % - -3. 33 % -2. 79 % - CHOPPER 22. 50 % 8. 91 % 8. 61 % 21. 59 % 8. 54 % 11. 80 % DTL -4. 14 % 9. 08 % 18. 99 % -6. 07 % 6. 18 % 16. 04 % CCDTL 2. 56 % 3. 14 % -1. 91% 4. 15 % 3. 92 % 0. 72 % PIMS 3. 27 % 1. 08 % -1. 18% 3. 04 % 1. 29 % -4. 21 % Total 22. 39% 20. 28% 24. 51% 37. 94% 36. 00% 24. 35% PIMS Conclusion The new layout of Linac 4 has been simulated from 45 ke. V to 160 Me. V with the codes Path Manager and Tracewin, and the performance will be compliant with the PSB requirements at the end of the Transfer Line. End-to-end simulation has shown that the beam losses are practically all in the RFQ and in the Chopper Line. The major RMS transverse emittance growth is in the Chopper Line. 24/09/2010