Low Energy operation of RHIC AGS low energy

Low Energy operation of RHIC AGS low energy extraction performance N. Tsoupas et. al. BNL

Purpose of the Study • To identify, and cope with, any issues related to the: – – injection in AGS acceleration extraction from AGS and transport to RHIC of p Cu and Au ions of Etotal ≥ 2. 5 Ge. V/nucleon. • If necessary, we may perform measurements to answer any questions relevant to the tasks mentioned above.

Schematic Diagram of the Collider Accelerator Complex TANDEM Tt. B If Booster can provide the required ion energy for RHIC, AGS can be used as a TRANSFER line and “Synchronize” Booster to RHIC Derek Lowenstein LINAC Bt B A Lt ER ST O BO AGS R At Injection into AGS same as in Normal Operations RHIC

Are there any problem relevant to beam Injection from the Booster to AGS? • There are NO problems relevant to the beam injection from Booster to the AGS. • In the past ions of p Cu and Au have been Injected in AGS and accelerated to a rigidity Br~85. [T. m] then transported to RHIC by the At. R beam transfer line. Vertical Acceptance of AGS at Injection 47 p[mm. mrad]

Schematic Diagram of the Fast Beam Extraction (FEB) from AGS 0 S DR=60 mm m ep tum . 45 H 1 128 R= G 1 0 K ick er Circulating bunch in AGS DR=45 mm S Ex m ro f ch ine n u Rl b d At e t c to tra AG AGS Circulating Beam Extracted Beam Vert. Accept. of AGS at Extracion 6. 3 p[mm. mrad] G 10_Kicker

Are there any problems relevant to beam Extraction from AGS at ion Energies 2. 5 Ge. V/nucleon? • Beam Emittance issue: – Beam emittance measurements of p Cu and Au ions during the acceleration show that the Normalized beam emittance is less or equal to the Normalized emittance at beam Extraction. – Vertical Acceptance of AGS at Extraction 6. 3 p[mm. mrad] G 10_kicker • There are ways to overcome the limit due to the Vertical acceptance of AGS if turns out to be a real issue.

Are there any problems relevant to beam Extraction from AGS at ion Energies 2. 5 Ge. V/nucleon? • Bunch length issues: – For a Au beam at energy 2. 5 Ge. V/nucleon, and longitudinal emittance of 0. 4 e. Vsec, computer simulations show that the “bunch length” is ~63 nsec. – “Quad pumping” is required to produce a Au beam of “bunch length” 32 nsec which is required to fit into the RHIC bucket. • Transition Energy issues: – If the required extraction energy from AGS coincides with the transition energy of AGS (Etot~8 Gev/n) , we can change the transition energy by changing the Horizontal tune of AGS. • Have we Extracted low Energy ions from AGS? • In the past, protons of K. E. 1. 6 Ge. V have been extracted from the AGS and transported to the “Neutrino Target” for the Radiography Experiment.

Issues Relevant to beam transport from AGS to RHIC “At. R” beam transfer line • The Vertical Acceptance of the At. R line is 6. 3 p[mm. mrad] and this limit is due to the gap of the 80 dipole. • The 197 Au+77 ions require stripping of the 2 electrons before RHIC Injection. A 100 mg/cm 2 Cu foil has ~80% efficiency for fully stripping Au ions of K. E~ 0. 5 Ge. V/n. The minimum K. E of the transported Au ions is ~1. 5 Ge. V/n and the stripping foil in the At. R line is ~50 mg/cm 2 thick tungsten. Thus we expect ~100% stripping efficiency. Measurements will be performed. • If the electrons of the Au ions present no problem in the circulating beam in RHIC it is advantageous to inject a more rigid beam into RHIC.

Summary • No issues releted to the beam injection from Booster to the AGS. • At ion Energies of 2. 5 Ge. V/n: – the “ 95%” beam emittance of p Cu and Au ions is almost the same as the acceptance of the AGS at extraction. – Optimization is required to minimize any beam losses during extraction. Study is recommended. – Quad pumping is required to minimize the bunch length of the beam. Study is recommended. • Beam transport in the At. R at beam Energies of 2. 5 Ge. V/n: – the “ 95%” beam emittance of p Cu and Au ions is almost the same as the acceptance of the At. R. – Optimization may be required to minimize any beam losses during extraction. Study is recommended. – Complete ion stripping of the 197 Au+77 ions is expected by the 45 mgr/cm 2 tungsten stripping foil of the At. R line.