Experience with low-energy gold-gold operations in RHIC during FY 2010

Longitudinal matching without gamma transition quads

“…This experiment, together with previous studies [1], indicates that longitudinal matching into the Yellow e-lens lattice can be achieved in spite of the higher horizontal tune. Figure 1: WCM after getting rid of the dipole oscillation above.…”

“…Since this raises γ t by about one unit, it needs to be ensured that longitudinal matching can still be achieved. In an earlier experiment [1], γ t had been lowered by ∆γ t = 0.35 by means of the γ t quadrupoles. In the experiment reported here, longitudinal matching was achieved by lowering the 9 MHz RF cavity voltage, while γ t was raised by 0.5 units to more closely simulate the conditions with the higher integer tunes.…”

Beam-Beam Effects in RHIC

“…11 , we observed a shorter beam lifetime of 7 hours compared to the 12 hours in the 2008 RHIC 100 GeV p-p run with β * = 1.0 m [3,4,5,6]. In the 2012 RHIC 100 GeV p-p run, β * = 0.85 m lattices were adopted, the beam lifetime was 16 hours with a typical bunch intensity of 1.65 × 10 11 [7].…”

RHIC Low Energy Acceleration

“…and the product of the β -functions at the IP and the triplets being nearly constant, 4) this limits the maximum allowable β -function in the triplets and therefore the luminosity. The individual ions in a round beam with radius a and uniform charge density η repel each other due to their equal charge, with the electrical field at a radius r < a inside the beam being…”

“…At the other two low energy points, 3.85 GeV/n and 5.75 GeV/n, much higher bunch intensities were successfully injected and stored [4]. At 3.85 GeV/n, the space charge limit was reached at ∆Q sc = 0.1 for bunch intensities beyond 0.7 · 10 9 Au ions/bunch, resulting in poor lifetime [5].…”