electron-ion collisions and other options for herahoff/talks/01-12-07/01_12_07durham.pdf ·...
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Electron-ion collisions and other options for HERA
ZEUSHERAH1 (318 GeV)
HERA-B (42 GeV)
HERMES (7 GeV)
PETRA
Grey College, Durham
12/07/2001
byGeorg H.
Hoffstaetter
[email protected]@desy.de
Development of the Luminosity
for HERA-I
Inte
grat
ed L
umin
osity
(1/
pb)
HERA Luminosity 1993-2000
Days after start of run
In 2000, design values have been surpassed for:
• specific luminosity• peak luminosity• integrated luminosity per year
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• Increase of luminosity from to
• Beam separation by super-conducting magnets in the detectors
• Focusing to ¼ of the old beam cross-section
The HERA Luminosity Upgrade
m
31105.1 ⋅ 31107 ⋅
New limitations:
• beam-beam tune shift
• hourglass effect for protons
• dynamic aperture of e-beam
• background due to radiation
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DataGauss fitGauss for proton emittances 16mum,electron emittances 21nm and 35% couplingGauss for proton emittances 16mum,electron emittances 21nm and 17% coupling
Lumi scan Nov. 2, 2001sL
)(mmx∆
-0.6 -0.4 -0.2 0 0.2 0.40
2.5 µ 10295 µ 1029
7.5 µ 10291 µ 1030
1.25 µ 10301.5 µ 1030
-0.3 -0.2 -0.1 0 0.1 0.2 0.30
2.5 µ 10295 µ 1029
7.5 µ 10291 µ 1030
1.25 µ 10301.5 µ 1030
)(mmy∆
sL
HERA and its Pre-Accelerator ChainH1
ZEUS
HERMES
HERA-B HERA
PETRA
778 m
6336 m long
DE
SY Polarized Electrons
Protons
Protons Electrons
20 keV Source Source 150 keV750 keV RFQ Linac II 450 MeV50 MeV Linac III Pia 450 MeV
8 GeV DESY III DESY II 7 GeV40 GeV PETRA PETRA 12 GeV
920 GeV HERA-p HERA-e 27.5 GeV
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Nominal and Ultimate Parameters
The performance goal of HERA is not unrealistic and should not be too hard to achieve.
A shortfall of beam intensity in the short term can be compensated.
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Increasing the Proton CurrentPETRA: N=60, 50 MHz 10 MHz & 5 MHz
10 MHz & 5 MHzN=30, 50 MHz
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l Polarized protons (30MEuro)l Polarized deuteronsl Electron precooling and coolingl Ion acceleration (53MEuro)
l Pulse stretcher for TESLAl Collisions with TESLA (120ME.)
HERA IIIPolarized protons in HERA
AApA LL 1311 107 ⋅⋅=⋅=
• Polarimeters• Flattening Snakes• Spin rotators• At least 4 Siberian Snakes [email protected]
31106.1 ⋅=epL
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Ions in HERA
8 GeV 40 GeV 920 GeV
HERAPETRADESY III
Linac IIIIon
Source
Challenges:l Longer bunch trains neededl Stronger space charge and IBSl Strong frequency swingl Croissing of transition energy neededl Long ramp cycles
sµ4530 −
%200=∆ff 5.6=> tγγ
min20=rampT
28=> tγγ
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Polarized Deuteronsl Resonances are 25 times
weaker and 25 times rarer for D than for p
l Transverse polarization could be achieved without Siberian Snakes
l Transverse RF dipoles could be used to rotate and stabilize longitudinal polarization
depolarizing resonance strength
depolarizing resonance strength
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Summary on e – Ion collisions
• Deuteron acceleration:Technical solutions seem possible
• Heavy ions: does not seem possible
• e – cooling counter balances IBS and leads to the required emittances and therefore
Ap /LL ≈
Ap /LL ≈
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e – cooling for HERA and PETRAl e – Ion: balances IBSl e – protons: doubles luminosityl e – polarized protons: reduces emittance to a polarizable size
l Cooling in PETRA:
m
m
py
px
µε
µεγ
8.05:
3.35:)19(
→
→≈ l Cooling in HERA:
preserve against IBS
m
m
py
px
µε
µε
9.0:
8.3:
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Cooling for e – Ion collisionsmmuGeVEA yx µεµε 25.0,1,/330:79197 ===+
12
1
−−⋅=
=
scmp
ApA
32100.76LLL
min18:
min30:.
====
coolIBS
coolIBS
vertical
horizon
ττττ
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[email protected]@desy.de
[email protected]@desy.de
THERA: The TESLA on HERA Collider
• Traveling focus:
• Cooling: m10/1 641
/−⋅=yxε
cm5.2/10/* ⋅=yxβ
• Luminosity: 1-231cm102 −⋅≈ sL
• Variable e-energies250-800 GeV
e/p IP
20MW e-dump
Injection
Damping ring
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TESLA with Röntgen FEL
Damping RingTunnel
Super-conducting Positron Linac
Wiggler for thePositron Source
Detector and Experimental Area
Cryogenic Halls
Super-conducting Electron Linac
Röntgen FEL