beam-beam experience in herahoff/talks/04_03_15eic_bb.pdf · [email protected] 03/15/2004...
TRANSCRIPT
03/15/2004
Beam-Beam Experience in HERA
Georg H.HoffstaetterCornell University(formerly DESY)
m
mm
mm
Electron-Ion ColliderWorkshop J-Lab 04
03/15/2004
ZEUSHERAH1 (318 GeV)
HERA-B (42 GeV)
HERMES (7 GeV)
PETRA
+(5$�XQGHU�+DPEXUJ
03/15/2004
Luminosity StudiesLuminosity Studies
H1 February 03 Extrapolated Luminosity vs Bunch Currents
0.00E+00
1.00E+31
2.00E+31
3.00E+31
4.00E+31
5.00E+31
6.00E+31
7.00E+31
8.00E+31
0 0.05 0.1 0.15 0.2 0.25
Ieb / mA x Ipb / mA
L /
cm-2se
c-1
Feb2003
Y2002 Goal
Design
Y2002 Studies
Series5
Feb 03 Studies
Absolute H1 Luminosity
0.00E+00
1.00E+31
2.00E+31
3.00E+31
4.00E+31
5.00E+31
6.00E+31
7.00E+31
8.00E+31
0 5000 10000
Ipb / mA x Ie / mA
Lu
min
osi
ty/c
m-2
sec
-1
Feb03 Run
Oct02 Studies
Design
Y2002 Goal
Feb03 Studies
Specific Luminosity vs Proton Intensity
0.00E+00
5.00E+29
1.00E+30
1.50E+30
2.00E+30
2.50E+30
3.00E+30
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8Ipb / mA
Lsp
/cm
-2se
c-1m
A-2
Feb-03
Y2002 Goal
design
Y2002Studies
Feb03Studies
120 Bunches
Ip < 70 mA
Ie < 35 mA
Lpeak<2.7 x 1031 cm-2s-1
120 Bunches120 Bunches
IIpp < 70< 70 mAmA
IIee < 35< 35 mAmA
LLpeakpeak<2.7 x 10<2.7 x 103131 cmcm--22ss--11
Specific Luminosity (1/cm2/s/mA2)
Proton bunch current (mA)
L (1
/cm
2 /s)
Luminosity extrapolation Luminosity (1/cm2/s)
Ipb X design Ieb (mA2)Ip X Ie(mA2)
03/15/2004
+(5$�,,,
Polarized protons in HERA e-A in HERA
• Deuteron acceleration:with same Linac
• Ion Acceleration requires:- a new Linac- high energy e-cooling
• Luminosity:
AApA LL 1311 107 ⋅⋅=⋅=
• Polarimeters• Flattening Snakes• Spin rotators• At least 4 Siberian Snakes
03/15/2004
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p beam
p beam
p beam
e
e
e beamp
e
h5.0=τ
h10=τ
h100=τ
h50=τ
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Electron bunch current (PA)
Pro
ton
lifet
ime
(h)
03/15/2004
Ls is independent of
e-current
/XPLQRVLW\�IRU�GLIIHUHQW�H�FXUUHQWV
Ls(1
/cm
2 /s2 /
mA
2 )
time (min)
03/15/2004
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Accumulated halo Newly produced halo
Tail scraping at HERA-B
t(s)
p bunch number p bunch number
HERA-B rates HERA-B rates
HERA-B rates
03/15/2004
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03/15/2004
3 Rotator Polarization Studies with Harmonic Bumps May 1, 2003
54%
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0
10
20
30
40
50
60
2/28
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14:5
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3/1/
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3/1/
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4:57
3/1/
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3/2/
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Date-Time
Po
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Explanation: The first fill and the refilling procedure have increased the proton emittances and decreased the beam beam force that acts on spins.
0 1 2 3 54 6 7 8 9
Ip
Ie
pol
Time(days)
03/15/2004
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• Beam beam tune shift for one particle in thebeam beam field of a Gaussian bunch:
• Shift in the dipole modes oscillationFrequency of a Gaussian bunch:
Assumption: the bunches remain Gaussian
)(2 pypxpx
ppb
e
e Nrexex σσσπγβξ +=
)(
)(
pypxpx
pypxpxexexQ
Σ+ΣΣ+
=∆σσσ
ξ
This approximation isjustified for a stiff beam hittinga much less stiff beam whenthe first beam creates a smallbeam beam kick.
03/15/2004
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Higher p current
Lower specific luminosity
Unexplained lumi change over each bunch train:
03/15/2004
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Ip( m
A)
Ip( m
A)
'4
ey(c
o mp.
,mea
s.)
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ex( c
o mp.
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s.)
Bunch number
03/15/2004
013.0=∆ simeyν
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041.0
==
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ex
ξξ
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009.0
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=∆mey
mex
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pxν
exνeyν
pyν
exex ξν − eyey ξν −
0/ ff x 0/ ff x
0/ ff x0/ ff x
003.0=∆ simexν
+why?
how ?
(From work with Jack Shi, KU)
082.0
027.0
==
ey
ex
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