recent pep-ii/babar operational parameters
DESCRIPTION
Recent PEP-II/BaBar Operational Parameters. W. Kozanecki, CEA-Saclay. Beam currents, luminosity, bunch pattern Typical backgrounds integrated dose beam aborts stored-beam backgrounds trickle backgrounds Collimation Vacuum history Heating issues. Luminosity. - PowerPoint PPT PresentationTRANSCRIPT
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Recent PEP-II/BaBar Operational ParametersRecent PEP-II/BaBar Operational Parameters
Beam currents, luminosity, bunch patternBeam currents, luminosity, bunch pattern
Typical backgroundsTypical backgrounds integrated dose
beam aborts
stored-beam backgrounds
trickle backgrounds
CollimationCollimation
Vacuum historyVacuum history
Heating issuesHeating issues
W. Kozanecki, CEA-Saclay
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Run 4 Beam-current & Luminosity HistoryRun 4 Beam-current & Luminosity History
LER total current
HER total current
Luminosity
W. Kozanecki BBBTF meeting, 28(27) Apr 04
W. Kozanecki BBBTF meeting, 28(27) Apr 04
W. Kozanecki BBBTF meeting, 28(27) Apr 04
IP Parameter Design Peak performance Apr 04
C-M energy (GeV) (e+: 3.1 ; e-: 9.0) 10.58 10.58Crossing angle (mrad) 0.0 < 1.0Luminosity (x 1033/cm2/s) 3.00 8.33
Number of bunches 1658 1549 LER current (mA, e+) 2146 2230 HER current (mA, e-) 750 1380 LER/HER current ratio 2.9/1 1.6/1
y*/x* (cm/cm) 1.5 / 50 1.1 / 48+, 1.1 / 28-Emittance (nm-rad) (y/x) 1.5 / 49 1.0 / 30+, 1.3 / 59-
LER tunes (x/y) 38.64 / 36.57 38.52 / 36.56HER tunes (x/y) 24.62 / 23.64 24.52 / 23.62Beam-beam parameter (vertical +/-) 0.03 0.067 / 0.046Beam-beam parameter (horizontal +/-) 0.03 0.086 / 0.032
PEP- II Collision Parameters (Apr 04)PEP- II Collision Parameters (Apr 04)J. Seeman, Apr 04
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Run-4 radiation dose-rate historyRun-4 radiation dose-rate history
HER trickle starts
HER trickle starts
Outgassing storms
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Integrated-dose historyIntegrated-dose history
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Stable-beam “genuine” radiation aborts: Stable-beam “genuine” radiation aborts: 0.9 / day
~ 60% of these may actually be sympathetic
““Genuine” injection aborts: 0.4 / dayGenuine” injection aborts: 0.4 / day
...to be compared to an average of 7 aborts/day from all sources...to be compared to an average of 7 aborts/day from all sources
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Stored-beam background historyStored-beam background history
SVT ocp’cy @ = (HEB-sensitive)
SVT ocp’cy @ = (LEB-sensitive)
20% 20%
Normalized DCH current
I DC
H, m
srd
/pre
d
10%
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Trickle-injection backgroundTrickle-injection background
The background generated by The background generated by the trickle injection is the trickle injection is concentrated in a narrow time concentrated in a narrow time window corresponding to window corresponding to revolutions of the injected revolutions of the injected bunch.bunch.
BABAR vetoes BABAR vetoes this windowthis window during data taking to avoid high during data taking to avoid high dead timedead time
BABAR rejects a larger region at BABAR rejects a larger region at the analysis phase to guarantee the analysis phase to guarantee good data quality. good data quality.
The total loss is around 1.5%The total loss is around 1.5%
Veto windowsVeto windows
W. Kozanecki BBBTF meeting, 28(27) Apr 04
LER collimatorsLER collimators PR04: 4 fixed: x,y,x,y (orbit bumps)
horizontal collimators useful to reduce beam-beam background.
vertical collimators sometimes help with the LER trickle backgrounds.
PR02: 2 adjustables (x) a major source of HOM heating.
can help with beam-beam tails in some subdetectors, but at the cost of swamping the IFR (and sometimes the DCH) with secondaries, so we use them very little move them elsewhere ?
HER collimatorsHER collimators PR12: 5 fixed: x,y,x,y,E
occasionally useful trickle, beam-beam
PR02: 2 adjustable (x) not useful
CollimationCollimation
HER collimators
LER collimators
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Ring-averaged presssure (Ring-averaged presssure (Jul 2000, Jul 2000, from inverse lifetime)from inverse lifetime)
LER lifetime
0
100
200
300
400
500
600
700
0 500 1000 1500
LER current (mA)
Lif
eti
me (
min
s)
No HER
Average LER pressure (from inv. lifetime)
0
1
2
3
4
5
6
0 500 1000 1500
LER current (mA)
<P
_LER
> (
nT N
2-e
q)
Msrd (LER only)
Fitted
Fitted pressure:p_b = 1.1 nT
p_d = 2.9 nT/A(summer 2000)
HER lifetime
0
200
400
600
800
1000
1200
1400
1600
1800
0 200 400 600 800HER current (mA)
Lif
eti
me (
min
s)
No LER
HER-averaged pressure (from inv. lifetime)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 200 400 600 800HER current (mA)
<P
_HER
> (
nT N
2-e
q.)
Data
Fitted
Fitted pressure:p_b = 0.84 nTp_d = 1.1 nT/A
(summer 2000)
2004: <p> < 0.9 nT @ 1 A
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Near-IR vacuum historyNear-IR vacuum history
LER current Incoming e+ (7 m
from IP, LEB-sensitive )
Outgoing e+ (7 m from IP, L+HEB-sensitive )
Incoming e- (17 m from IP, HEB-sensitive )
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Thermal time constants: a problem!Thermal time constants: a problem!
VGCC2187 (HER sensitive)
BW diamond [+ BBR dead time] (HEB sensitive)
VGCC3027 (incoming
LEB)
BE diamond (LEB sensitive)
LER current
12 hours
W. Kozanecki BBBTF meeting, 28(27) Apr 04
LER current 2.2 A 3027 = 268°F 3044 = 453°F
3053 = 425°F 3081 = 724°F
LER NEG temperatures
#1 #2
#3 #4
W. Kozanecki BBBTF meeting, 28(27) Apr 04
IIR Heating Issues - OverviewR Heating Issues - Overview
HOM Heating HOM Heating Vertex Bellows Cooling Addition 2002 is working well Q1/Q2 Bellows
Larger HOM absorbers in 2002, Cooling and monitoring improved. Will need to improve HOM/Power capability - now 10 KW
Synchrotron Radiation and Orbit ConstraintsSynchrotron Radiation and Orbit Constraints Require LEB aimed at Luminosity Monitor IP angles constrained by backgrounds LEB B1 Fan Hits LEB Leg of Q2 Crotch and Q4 chamber
May be cause of magnet motion (~20 microns). HEB – B1 fan aimed at High Power Dump must miss Q5R chamber flange
Vacuum and BackgroundsVacuum and Backgrounds HOM Heating of NEG and Increased Backgrounds
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Spare slidesSpare slides
W. Kozanecki BBBTF meeting, 28(27) Apr 04
Near IRNear IR