Overview Run-6 - RHIC Overview Run-6 - RHIC
Vadim Ptitsyn
C-AD, BNL
RHIC Spin Workshop 2006
V.Ptitsyn
RHIC Run-6 TimelineRHIC Run-6 Timeline
1 Feb – Start of the Run-6. Start of the cooldown to liquid He temperatures. 12 Feb - End of cooldown and PS tests 5 Mar – Start of the 100 GeV Physics Run. Participating experiments: STAR and PHENIX. PHENIX – radial pol ; STAR – long pol 6 Apr – PHENIX – radial pol ; STAR – vertical pol 14 April –21 April – unscheduled shutdown (investigation of electric accident) 26 Apr – PHENIX – longitudal pol; STAR – vertical pol 10 May – PHENIX – longitudal pol; STAR – longitudinal pol 5 Jun – End of 100 GeV run. (12 weeks total ) 5 Jun-6 Jun, 11 GeV accelerator development 6 Jun – Start of 31.2 GeV Physics Run. Participating experiments: STAR, PHENIX and BRAHMS PHENIX – longitudal pol; STAR and BRAHMS– vertical pol 20 Jun - End of 31.2 GeV Run. (Two weeks total) 20 Jun – 26 Jun. 250 GeV accelerator development 26 Jun - 30 Jun warm-up to liquid N temperatures. 30 Jun - End of Run-6. (21.2 weeks of cryo operation)
RHIC Spin Workshop 2006
V.Ptitsyn
Physics run lattices Physics run lattices
IP6 IP8 IP10 IP12 IP2 IP4
Injection 10 10 10 10 10 10
Store, 100 GeV 1 1 10 10 10 10
Store, 31.2 GeV 3 3 10 10 3 10
Lattice modifications:- minimized excursion of dispersion function in IR6 and IR8 in the store at 100GeV
- decreased gamma_t lattice at the injection
Working points: (0.72-0.73) box at the injection; (0.68-0.695) box at the storeTune swing done: 100GeV: at the very end of the acceleration, but before final beta-squeeze part of the ramp
31.2GeV: right before the last stone of the ramp
Beta* configuration (in meters):
RHIC Spin Workshop 2006
V.Ptitsyn
Polarized protons performance at 100 Polarized protons performance at 100 GeV (last three runs)GeV (last three runs)
Parameter Unit 2004 20052005 20062006
No. of bunches -- 56 106106 111111
bunch intensity 1011 0.7 0.90.9 1.351.35
* m 1 1 1 1 1
emittance mm mrad 18 2828 1818
peak luminosity 1030cm-2s-1 6 1010 3535
average luminosity 1030cm-2s-1 4 6 6 20 20
collision points -- 4 33 22
time in store % 41 5656 4646
average polarization, store
% 46 4747 65%65%
Luminosity gain in run-6:
2.2 X 1.5 = 3.3
Increased bunch intensity Improved emittance control
AGS cold snake:polarization
Reduced number of collision points
RHIC Spin Workshop 2006
V.Ptitsyn
Integrated luminosity; 100 GeV runIntegrated luminosity; 100 GeV run
Run6 100 x 100 GeV pp Integrated Luminosity (Final Delivered) for Physics
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
4-M
ar
11
-Ma
r
18
-Ma
r
25
-Ma
r
1-A
pr
8-A
pr
15
-Ap
r
22
-Ap
r
29
-Ap
r
6-M
ay
13
-Ma
y
20
-Ma
y
27
-Ma
y
3-J
un
date
Inte
gra
ted
Lu
min
os
ity
[p
b^
-1]
STAR
PHENIX
min
max
one week shutdown
RHIC Spin Workshop 2006
V.Ptitsyn
Average integrated luminosity per store Average integrated luminosity per store hour and Time in storehour and Time in store
8 weeks luminosity improvement period
Considerable amount of down time in the middle and at the end of the run
Luminosity slides at the end of the run due to longer stores
RHIC Spin Workshop 2006
V.Ptitsyn
Golden store #7909 of 100 GeV runGolden store #7909 of 100 GeV runL
umin
osity
RHIC Spin Workshop 2006
V.Ptitsyn
polarization for Run 6, 100x 100 GeV - final
0
10
20
30
40
50
60
70
80
2/12/060:00
3/4/060:00
3/24/060:00
4/13/060:00
5/3/060:00
5/23/060:00
6/12/060:00
aver
age
% p
olar
izat
ion
for
each
sto
re
Run-5Average Pol49%45%
Polarization during 100 GeV runPolarization during 100 GeV run
RHIC Spin Workshop 2006
V.Ptitsyn
100 GeV run: Luminosities and 100 GeV run: Luminosities and transverse emittancestransverse emittances
Improved transverse emittance control was important item at this run
During the run the improvements to achieve smaller transverse emittance were done both in the injectors and in the RHIC:•Transverse scraping in Booster•Strict control of emittance from AGS (golden values) •appropriate choice of working point (to avoid coherent beam-beam)•keeping bunch length long enough
W.Fischer
RHIC Spin Workshop 2006
V.Ptitsyn
Transverse emittanceTransverse emittance Run-5 emittance
troubles: Larger emittance with
larger number of bunches
Larger emittance from AGS on several fills
In Run-6 those problems were avoided
Helped by vaccuum system improvements:
additional NEG pipe coating (180m) added between the runs
upgrade in cold region vaccuum
S.Y.Zhang
RHIC Spin Workshop 2006
V.Ptitsyn
Integrated luminosity; 31.2 GeV runIntegrated luminosity; 31.2 GeV run
Run6 RHIC pp Integrated Luminosity for Physics (Final)31.2 x 31.2 GeV
0
100
200
300
400
500
600
7-Jun
8-Jun
9-Jun
10-Jun
11-Jun
12-Jun
13-Jun
14-Jun
15-Jun
16-Jun
17-Jun
18-Jun
19-Jun
20-Jun
Del
iver
ed (
Ph
ysic
s) I
nte
gra
ted
Lu
min
osi
ty [
nb
^-1
]
STARPHENIXBRAHMSMinMaxPoly. (Min)Poly. (Max)
RHIC Spin Workshop 2006
V.Ptitsyn
Major operation achievementsMajor operation achievements Successful application of tune/decoupling feedback for the initial ramp
development. Fast collimation. Regular orbit correction at the beginning of the store (before the
cogging) to provide the store reproducibility against 24h orbit variation. IR nonlinear corrections: used not only at the store but also on the ramp
(after the beta-squeeze). 2/3 resonance correction Successful demonstration of “quad pumping” technique to provide better
AGS-to-RHIC longitudinal emittance matching. Unfortunately, could not be effectively used because of the transverse emittance deterioration.
Developed Beam Transfer Function measurement diagnostic. Rotator reconfiguration (done 5 times during the run). Takes 8h + 2-3 stores.
RHIC Spin Workshop 2006
V.Ptitsyn
Factors limiting machine performanceFactors limiting machine performance
Store lifetime: Qx=2/3 resonance beam-beam effects large momentum spread
Factors affecting transverse emittance: small longitudinal emittance and higher beam intensity (enhanced electron
cloud effect) emittance increase on the ramp (?)
Deterioration of ramp transmission with the beam intensity Beam oscillations with parasitic frequencies 10Hz, 60Hz,
…
(coming from cryo and power supply systems)
RHIC Spin Workshop 2006
V.Ptitsyn
Further plansFurther plans Christoph Montag is the Run coordinator for next polarized proton run. Goal: doubling the luminosity, by bunch intensity increase and increased time in store
RHIC Spin Workshop 2006
V.Ptitsyn
Luminosity improvement factors for Luminosity improvement factors for next runnext run
Nonlinear chromaticity correction 10Hz IR orbit feedback 2/3 resonance compensation New working point test, ~(0.92;0.93) Additional NEG pipes (~45m)
Reliability of various machine systems is seriously addressed in this shutdown.
In more remote plans the application of new 9.3Mhz RF cavity system is considered (M.Brennan).
This should allow for smaller longitudinal emittance and smaller bunch length in the store, but long enough bunch length at the injection.
RHIC Spin Workshop 2006
V.Ptitsyn
ConclusionsConclusions
On accelerator part we believe the run was quite successful. Good side: Luminosity goals are achieved. Improved machine
parameters (beam intensities, emittances, polarization). Bad side: Machine reliability problems. Goal for the time in store was
not achieved.
Continue go forward. For next run: Further luminosity improvements (by factor 2). Improved machine reliability