Measurements of Longitudinal Emittance of Au⁷⁷ in the AGS

Technical Report · Tue Dec 07 04:00:00 EST 1993

DOI:https://doi.org/10.2172/1132389· OSTI ID:1132389

Brennan, J. M. ^[1]; Deng, D-P. ^[1]; Rose, J. ^[1]

---

1. Brookhaven National Laboratory (BNL), Upton, NY (United States)

The AGS must supply heavy ion bunches to the RHIC with a longitudinal emittance of 0.2 eVs/nucleon. This specification follows from two considerations. First, in crossing the gamma transition in RHIC chromatic nonlinearites lead to beam loss if the momentum spread in the beam is too big. Second, the luminosity is inversely proportional to the bunch length and the bunches are kept short by storing them in buckets of the 200 MHz rf system. The emittance must be small in order to pass the bunches from the 26 MHz accelerating system to the storage system ("rebucketing") without spilling into adjacent buckets. In the AGS for SEB the primary consideration is effective debunching, to eliminate rf and revolution frequency structure from the spill. This consideration favors large longitudinal emittance, limited by the bucket area the rf cavities can provide. For the fixed-target SEB run of FY93 with Au⁷⁷ ions, the rf system was configured for 12 equally populated buckets with 0.4 eVs/nucleon bunches. (Note that this is equivalent to 1.6 eVs/nucleon/bunch if the beam were in three bunches, the canonical RHIC mode.) This was accomplished by non-adiabatically debunching the beam injected from the Booster (one-quarter of the ring) to fill the AGS ring with coasting beam and then adiabatically capturing the beam into 12 bunches.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1132389
• Report Number(s): BNL--104183-2014-IR; AGS-310
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS