Beam Backgrounds
at a SuperB Factory
Aaron Roodman
Stanford Linear Accelerator Center
SuperB workshop
March 17, 2006
D
—0.0—
—0.0—
4.76 +- 0.21
E
—0.0—
—0.0—
-0.96 +- 0.25
—0.0—
3.97 +- 0.06
—3.966—
—3.966—
—3.966—
—3.966—
—3.966—
—3.966—
3.97
—0.0—
—0.—
—0.00—
—0.00—
—0.00—
—0.00—
—0.00—
—0.00—
0.
Single beam LER
Single beam HER
F No quadratic terms
—0.0— Single beam LER
—0.0— Single beam HER
—0.0—
Lumi HER 2/3, LER scan
Lumi
—0.0— HER max, LER scan
—0.0—
Lumi LER 2/3, HER scan
0.460 +- 0.015
Lumi LER max, HER scan
0.372 +- 0.012
Lumi trickle, HER scan
0.393 +- 0.015
0.525 +- 0.011
All good Lumi points
0.555 +- 0.015
Preferred result
—0.606—
—0.606—
0.21 +- 0.07
—0.0—
-0.03 +- 0.05
—0.0—
—0.0—
4.76 +- 0.21
—0.0—
-0.96 +- 0.25
—0.0—
—0.0—
—0.0—
—0.—
—0.00—
—0.00—
—0.00—
—0.00—
—0.00—
—0.00—
0.
—0.0—
—0.0—
0.460 +- 0.015
0.372 +- 0.012
0.393 +- 0.015
0.525 +- 0.011
0.555 +- 0.015
0.420 +- 0.007
0.42
Beam Background Sources
227
131
36
47
139
116
118
348
—0.606—
—0.606—
—0.606—
—0.606—
—0.606—
—0.606—
—0.606—
—0.606—
0.61
0.166 +- 0.018
—0.0—
—0.166—
—0.166—
—0.166—
—0.166—
—0.166—
—0.166—
0.17
—0.—
—0.0—
—0.00—
—0.00—
—0.00—
—0.00—
—0.00—
—0.00—
0.
—0.0—
3.97 +- 0.06
—3.966—
—3.966—
—3.966—
—3.966—
—3.966—
—3.966—
3.97
Extrapolate from PEP-II look at DCH backgrounds
0.420 +- 0.007
0.42
Occupancy(%)
HER + 0.42 L
Lumi trickle, HER scan
6
Single beam LER
Entries
Mean x
Mean y
RMS x
RMS y
0
0
0
5
4
Single beam HER
1865
3523
2.092
1905
0.9662
1
0
1864
0
0
0
Occupancy (%)
2559
1067
0.7881
463
0.3099
1
0
2558
0
0
0 10
3
2
10
5
4
10
1
0
0
2301
0
2301
588.1
2.98
318.9
1.193
0
0
0
10
3
-1
0
2000
000
urrent (mA)
4000
6000
Luminosity (1e33)
2
1
Luminosity Backgrounds at PEP-II
Drift Chamber performance
1000
Entries
Mean x
Mean y
RMS x
RMS y
0
0
0
5
4
1865
3523
2.092
1905
0.9662
1
0
1864
0
0
0
10
3
2
1
Michael Sullivan
0
HERRadiative
LER
Radiative
Radiative
Bhabhas
Bhabhas
PEP-II
Bhabhas
30
-1
2.5
7 / 28
1
500
Lumi trickle, HER scan
6
Using ILER = 1.0 A IHER=1.0 A L=1036 implies
a DCH Occupancy of 400%, all from Luminosity
Entries
Mean x
Mean y
RMS x
RMS y
0
0
0
6
1
1
Cristinziani, Hawaii workshop
= 0.61 + 0.17 ILER + 3.97 IHER + 0.42 L
+0.21 ILER (beam − beam)+0.03 L (trickle injection)
Occupancy - Single Beam contribution (%)
Occupancy - Single Beam contribution (%)
m)+0.03 L (trickle injection)
ries
an x
an y
Sx
Sy
0
0
0
227
117
1500
2000
LER current (mA)
0
1
1
0
500
3
20
1000
HER current (mA)
0
2000
IP Bends put Radiative Bhabhas
into the magnets
- full Geant
Markus Cristinziani
BaBar Drift Chamber performance
simulation reproduces Luminosity
Background to within a factor
4000
6000
Luminosity (1e33)
0.5
1
1
3.
1.5 2
3.5
eV
G
4
10
cm
0
6
6.5
7
7.5
8
4.5
5 5.5
7 / 28
9 GeV
9 GeV
-10
-20
need to evaluate SuperB IP design
Aaron Roodman
Stanford Linear Accelerator Center
-30
-7.5
1
3.
3
eV
G
0.5
2 1.5
1
2.5
-5
-2.5
SuperB Workshop
0
m
2.5
5
7.5
M. Sullivan
Feb. 8, 2004
API88k3_R5_RADBHA_TOT_7_5M
Beam Related Backgrounds
Beam Background Sources
Super-KEKB design at Now!!
Extrapolate from Super KEK-B study
Average Vacuum 5x10-7 Pa
KEKB
Tajima Hawaii workshop
ILER = 9.4A IHER =4.1 A
Radiative Bhabha backgrounds
limited to Muon system, after
shielding the calorimeter
1st layer
Touschek scattering
Intra-bunch scattering: Linear in bunch volume, quadratic in current
with σy = 12nm becomes a much more serious issue
Beam-Gas will not be as large at SuperB, with lower Beam currents
Aaron Roodman
Stanford Linear Accelerator Center
SuperB Workshop
Beam Related Backgrounds
Estimating Backgrounds at SuperB
Andrei Seryi - scaled ILC final focus design to SuperB energy
Takashi Maruyama - converted MAD deck to GEANT model of IP
GEANT model of IP
x view:
y:
develop tools to study SuperB backgrounds
start with Radiative Bhabha and Touschek sources
of background from the IP model
feed into current BABAR/PEP-II GEANT model
(modify permanent magnets to superconducting)
Aaron Roodman
Stanford Linear Accelerator Center
SuperB Workshop
Beam Related Backgrounds