APEX Report April 28-29, 2009 May 4, 2009 Fulvia Pilat Time Meeting, May

APEX Schedule April am9pm7pm11:30pm Injection 08-29, Polarimeter study Huang, Zelenski +team 2am Ramps BBQ DA measurement with AC dipole Bai Pilat 7am Injection BBQ 10 6 turn BPM AC dipole 07-19, Noise from Main PS Schultheiss Minty D0-DX study MacKay Satogata Long Range beam-beam Fischer +team Store BBQ Injection

APEX Schedule May 4 th amnoon Injection 3pm Ramps BBQ 4pm 07-19, Noise from Main PS Schultheiss Wilinsky D0-DX study MacKay Satogata

RHIC/AGS Polarimeter Study Fixed target polarization for two intensities (1.4 and 1.6*10 11 ) with 12 bunches in both rings with two polarimeters. AGS measurements were done with similar intensity. Polarization profile measurements were done with both rings and both planes with 56 bunches. AGS horizontal and vertical profiles were taken the same time. Sweep and fixed target measurements were done with 56 bunches for comparison. Note: Keith tuned emittance down for AGS before the study, we did not see much change on AGS IPM or CNI target scan, but the polarization profiles measured in AGS is flatter than before. Huang, Zelenski+team

Polarization Profiles of RHIC and AGS Ring Horizontal P 0 sigma Vertical P 0 sigma AGS Blue Blue Yellow The profiles are consistent between AGS and RHIC with the statistics. The  actually is  P /  I. These numbers from last year at 100GeV are averaged 2.5, this year is about 3(average of many fills). Given the large error bars, I can’t say there is profiles developed in RHIC ramp.

PS beam noise - summary Four ramps were executed with different configurations of the electrostatic shield and a capacitor across the grounding resistors. Schultheiss, Minty

Ramp 1 Results

Conclusions Floating the Electrostatic Shields in the Dipole Ramp PM reduced the noise during the ramp. Yellow showed more reduction than Blue. The Capacitor had a less dramatic reduction in the noise. The present configuration is with the shields floating and no capacitor.

Plan for the experiment Use pattern BBLR_34x34 (28x non-colliding bunches), 2e 11 /bunch, accelerate and collide, will not ramp up the RF voltage CNI emittance measurement => emittances measured around 35 (Blue) and 22 (Yellow) mm.mrad : BBQ was left one during the ramp 5A, position scan in Blue and Yellow, orbit and BTF measurements Retract, CNI emittance measurement => around 50 (Blue) and 22 (Yellow) mm.mrad 50A, position scan in Blue and Yellow, orbit and BTF measurements Retract, CNI emittance measurement Time permitting, change chromaticity, repeat one scan Fischer Robert-Demolaize Calaga

Conclusion Plan executed: distance scans with both 5A and 50A scans in both beams, including head-on beam-beam. Suffered from larger than usual emittance (about 30 mm.mrad); BBQ should be off next time. Additional beam time to study in details the behavior of non-colliding bunches + chromaticity changes ?

MacKay, Satogata

APEX Schedule May am10pm7pm1am Injection High intensity 3am Space charge and Beam-beam Fedotov + team 7am Off-momentum beta-beat Calaga Glenn Long Range beam-beam Fischer Demolaize +team Store BBQ Injection High intensity Gamma-T No snakes Bunch length limit Ptitsyn+ team Impedance Calaga