M. LindroosNUFACT06 School A low energy accumulation ring for the beta-beam Ansgar Simonson, Anders...
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Transcript of M. LindroosNUFACT06 School A low energy accumulation ring for the beta-beam Ansgar Simonson, Anders...
![Page 1: M. LindroosNUFACT06 School A low energy accumulation ring for the beta-beam Ansgar Simonson, Anders Kaellberg, Mats Lindroos.](https://reader035.fdocuments.us/reader035/viewer/2022062721/56649f225503460f94c3b57b/html5/thumbnails/1.jpg)
M. Lindroos NUFACT06 School
A low energy accumulation ring for the beta-beam
Ansgar Simonson, Anders Kaellberg, Mats Lindroos
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M. Lindroos NUFACT06 School
Outline
• General concepts: LEIR and HESR• Application to a beta-beam• First results for 18Ne
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M. Lindroos NUFACT06 School
The EURISOL beta-beam facility!
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M. Lindroos NUFACT06 School
Production
• Major challenge for 18Ne• Workshop at LLN for production,
ionization and bunching this year• New production method proposed by
C.Rubbia and Y.Mori• Accumulation ring?
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M. Lindroos NUFACT06 School
The slow cycling time.What can we do?
Production
PS
SPS
Decay ring
Ramp time PS
Time (s)0 8
Wasted time?
Ramp time SPS
Reset time SPS
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M. Lindroos NUFACT06 School
Production and accumulation
PS
SPS
Decay ring
Ramp time PS
Time (s)0 2.4
Ramp time SPS
Reset time
4.8 7.2
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M. Lindroos NUFACT06 School
Accumulation at 400 MeV/u
2 4 6 8 10
Accumulationtime
21018
41018
61018
81018
11019
1.2 1019
Annualrate 6HeT1/2=1.67 s
T1/2=17 s
T1/2=0.67 s
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M. Lindroos NUFACT06 School
Stacking
0.2 0.4 0.6 0.8 1
25000
50000
75000
100000
125000
150000
Multiturn injection with electron cooling
Half life [s] 0.1 1 10Tvacuum [s] 30 30 30Intensity ions [every 100 ms in 30 microsceonds] 104 5 105 5 105
Tcool[ms] 100 100 100Number of turns 10 10 10Final emittance [micrometer] 0.1 0.1 0.1Final number of particles in stack 3 104 3 107 3 108
2 4 6 8 10 12
Time [s]
0
2
4
6
8
Beam
Inte
nsity [
E8 ions]
beam lifetime : 6.5s
Linac III rep rate : 2.5 HzIon beam energy : 4.2 MeV/uElectron energy : 2.35 keVElectron current : 105 mA
Average accumulated intensity : 6E8 ionsPeak intensity : 7.1E8 ions
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M. Lindroos NUFACT06 School
Electron Cooling before the RCS
• Can the beams be cooled transversely in 0.1 s?
• Ansgar Simonsson, Anders Kallberg
• 22 May 2006
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M. Lindroos NUFACT06 School
Scenario20 cycles during 2 s, then 5 s pause
10 Hz linac cooler ring RCS PS 100 MeV/u 100 MeV/u 300 MeV/u
Accumulation Several linac buches are merged in the cooler
ring with electron cooling for every bunch sent to the RCS
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M. Lindroos NUFACT06 School
• A 430 m cooler ring from FAIR
• one 30 m long electron cooler
• one section for injection and extraction
The RCS is 208 m, the cooler ring can be e.g. 104 m or 208 m.
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M. Lindroos NUFACT06 School
Electron cooling
fast for cold ions, slower when electron and ion velocities differ
not dependent on ion current
much faster longitudinally than transversely
1/cooling time ~ q2/A×Ie/Θ3, where Θ is the angle between ions and electrons
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M. Lindroos NUFACT06 School
Emittance
Intensity
Before cooling
After cooling
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M. Lindroos NUFACT06 School
Electron cooler
the cooling section is one to several meters long
up to 2.5 A electron current
55 kV for 100 MeV/u
large -functions give fast cooling, 1/cooling time ~ 1/Θ3 ~ 1.5
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M. Lindroos NUFACT06 School
Simulations of transverse cooling
input: hollow ion beams so all ions have the same transverse emittance
simple tracking with 3 D cooling force and electron beam space charge
intrabeam scattering isn’t included, so the results for the coldest ions are wrong
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M. Lindroos NUFACT06 School
18Ne10+ 0.1 s cooling 10% electron cooler2.5 A electron currentx = 16 mx = 100 p mm mrad
PS limit 16 mm / 7 mm
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M. Lindroos NUFACT06 School
6He2+ vs 18Ne10+
1/cooling time ~ q2/A (theory) or1/cooling time ~ q1.7/A (CRYRING
measurements)
18Ne10+ / 6He2+= 5 - 8, cooling of neon is much faster
Space charge tune shiftQ = -0.022 / -0.14
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M. Lindroos NUFACT06 School
6He2+ 0.1 s cooling 10% electron cooler1 A electron currentx = 16 mx = 100 pi mm mrad
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M. Lindroos NUFACT06 School
Conclusions
• A cooling ring with multiturn injection before the RCS can dramatically reduce the horizontal emittance of 18Ne10+ with 0.1 s cooling.
• The 6He2+ case is much more difficult, since the cooling time is longer and the space charge tune shift larger.
• A factor of 4 of the “missing” 18Ne in the decay ring can be recovered using this technique