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

2. 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 E total ≥2.5 GeV/nucleon. If necessary, we may perform measurements to answer any questions relevant to the tasks mentioned above.

3. RHIC LINAC TANDEM AGS BOOSTER TtB LtB BtA AtR Schematic Diagram of the Collider Accelerator Complex Injection into AGS same as in Normal Operations 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

4. 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 B  ~85.[T.m] then transported to RHIC by the AtR beam transfer line. Vertical Acceptance of AGS at Injection 47  [mm.mrad]

5. Schematic Diagram of the Fast Beam Extraction (FEB) from AGS R=128.45 m  R=60 mm AGS Extracted bunch from AGS to AtR line H10 Septum G10 Kicker Circulating bunch in AGS  R=45 mm Circulating Beam Extracted Beam Vert. Accept. of AGS at Extracion 6.3  [mm.mrad] G10_Kicker

6. Are there any problems relevant to beam Extraction from AGS at ion Energies 2.5 GeV/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] G10_kicker There are ways to overcome the limit due to the Vertical acceptance of AGS if turns out to be a real issue.

7. Are there any problems relevant to beam Extraction from AGS at ion Energies 2.5 GeV/nucleon? Bunch length issues: –For a Au beam at energy 2.5 GeV/nucleon, and longitudinal emittance of 0.4 eVsec, 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. Have we Extracted low Energy ions from AGS? In the past, protons of K. E. 1.6 GeV have been extracted from the AGS and transported to the “Neutrino Target” for the Radiography Experiment. Transition Energy issues: –If the required extraction energy from AGS coincides with the transition energy of AGS (E tot ~8 Gev/n), we can change the transition energy by changing the Horizontal tune of AGS.

8. Issues Relevant to beam transport from AGS to RHIC “AtR” beam transfer line The Vertical Acceptance of the AtR line is 6.3  [mm.mrad] and this limit is due to the gap of the 8 0 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 GeV/n. The minimum K.E of the transported Au ions is ~1.5 GeV/n and the stripping foil in the AtR 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.

9. Summary No issues releted to the beam injection from Booster to the AGS. At ion Energies of 2.5 GeV/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 AtR at beam Energies of 2.5 GeV/n: –the “95%” beam emittance of p Cu and Au ions is almost the same as the acceptance of the AtR. –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 AtR line.