posipol workshop 2010

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23th July 2010CLIC meeting L. Rinolfi

POSIPOL workshop 2010

L. Rinolfi

A brief overview

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POSIPOL is a series of workshops dealing with the physics aspects, the design issues, and the open questions concerning polarized positron sources in the framework of the ILC and CLIC projects. POSIPOL 2010 was the fifth workshop following:

POSIPOL 2006 at CERN Chair: L. RinolfiPOSIPOL 2007 at LAL-Orsay Chair: A. VariolaPOSIPOL 2008 at Hiroshima Chair: M. KurikiPOSIPOL 2009 at IPNL-Lyon Chair: X. ArtruPOSIPOL 2010 at KEK Chair: T. Omori

Short history

POSITONS POLARISÉS

(in French)

April 2006

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Participants POSIPOL 2010

44 participants (4 from CERN):

M. Petrarca, L. Rinolfi, A. Vivoli, F. Zimmermann

19 Institutes (from America, Asia, Europe):

ANL, BINP, BNL, CERN, DESY, Hiroshima University, IHEP, IPNL/IN2P3, INFN, ISIR, JAEA, KEK, LAL, LLNL, NSC/KIPT, RISE, Tokyo University, Tomsk, Waseda University.

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Scope of the workshop

POSIPOL 201031/May-2/June, KEK, Tsukuba

T. Omori

POSIPOL 2010 focuses, as in the previous years, on polarized positron sources for ILC and CLIC via Laser-Compton and via undulator-radiation, but also extends topics as target discussions particularly relevant for the conventional positron sources.

For these later, various solid and liquid target materials and pseudo-conventional using channeling are topics of the workshop. POSIPOL 2010 deals also with various high intensity positron sources for other future collider projects, such as B-factories and LHeC.

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Japan Proton AcceleratorResearch Complex : J-PARC

Mt. Fuji

NaritaTokyo

Kamioka TokaiTsukuba

ee--/e/e++ Collider ColliderB-FactoryB-Factory

Photon-Factory

ILC-Test Facility

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• The JAHEP community’s master plan• Highest priority is given to ILC• Before ILC, promote flavor physics at KEKB and J-

PARC

• Action before the ILC approval• ILC R&D• Completion/commissioning and continuous

improvements of J-PARC• Upgrade of KEKB/Belle• Collaboration in LHC/ATLAS

Koichiro Nishikawa

News from IPNS director

IPNS = Institute of Particle and Nuclear Study

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Physics: (1 talk)

Status of e+ sources for colliders :(4 talks: ILC, CLIC, KEKB, BEPC)

ILC-CLIC working group : (1 talk)

Hybrid and channeling e+ sources (CLIC&ILC): (7 talks)

Compton-based e+ sources for colliders (ILC&CLIC):(10 talks)

Undulator-based e+ source for ILC:(4 talks)

Compton-based X-ray and gamma-ray sources : (4 talks)

(including applications to material physics)

Liquid Pb and Pure Conventional e+ sources (ILC): (3 talks)

What was discussed

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Why polarized e- and e+ beams ?

G. Moortgat-Pick

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LC Strategy G. Moortgat-Pick

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Arguments for polarized e+

G. Moortgat-Pick

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•Undulator •Located at 150GeV point in electron linac•Helical•Pitch = 1.15cm, B=0.86T (K=0.92)•Beam aperture 5.85mm

•Target•Ti Alloy•Wheel with radius 1m, thickness 1.4cm•Rotating speed 100m/s (2000rpm)

•Capture •Flux concentrator

•KAS (Keep Alive Source)•Independent, conventional•10% intensity

ILC - RDR designKaoru Yokoya

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1) Replace flux concentrator with QWT. Accordingly, undulator length 147m231m to compensate for the less efficient capture.. This does not mean QWT+231m undulator is less risky than FC+147m undulator

(Just because feasibility demonstration of FC is more costly). Higher target load due to longer undulator (x 1.6)

2) Move undulator to linac end •One MPS•Shorter positron transport•No deceleration needed•Everything dirty is concentrated near the center of the complex (BDS,

DR, injectors)

3) Keep Alive Source (~10% intensity) replaced by Auxiliary Source (few % intensity) which shares the target, capture system, etc with the undulator source

Kaoru Yokoya

ILC - SB2009 DesignNot yet the baseline

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e-/Target Pre-injector

e+ Linac200 MeV

Primary e- Beam Linac5 GeV

Inje

ctor

Lin

ac

2.66

GeV

e+ PDR

2 GHz 2 GHz

2.86 GeV

e

Target

AMD

unpolarized e+

Bunching system

Thermionic e- gun

4.6x109 e+ / bunch

Energy 2.86 GeV

Positron yield (e+/e-) 0.7

Charge 7x109 e+/bunch

Normalized rms emittances 7300 mm.mrad

Energy spread (rms) 113 MeV

Bunch length (rms) 5.3 mm

Longitudinal rms emittance 0.55 m.MeV

polarized e-

CLIC - CDR Design - 3 TeV

at PDR injection

Primary e- beam energy

5 GeV

Number e- / bunch 1010

Source of photons W crystal (1.4 mm)

Target for e+ production

W Amorphous target (10 mm)

Target material (thickness)

W (3 o)

Magnetic field capture system

AMD (6 to 0.5 T)

RF capture system 10 MV/m

at Source

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SuperKEKB e+ source upgrade

T. Kamitani

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T. Kamitani

Status of SuperB factories

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Parameters Design Test results BEPC

Energy （ GeV） 1.89 1.89 1.30-1.55

Current (mA) e+ 37 66 ~5

e- 500 550 300

Emittance （ 1σ, mm-mrad）

e+ 0.40 0.35 ~ 0.27 ----

e- 0.10 0.097~0.079 ----

Energy spread (1σ, %)

e+ 0.50 0.371 ~0.80

e- 0.50 0.295 ~0.80

Energy stability ( % )

0.15 0.05 ----

Orbit stability (mm)

0.30 0.119 ~0.058 ----

Repetition rate 50 50 12.5

e+ injection rate（ mA / min.)

50 61.5 1 ~ 3

Status of BEPC IIG. PeiImpressive progress from BEPC to BEPC II at Beijing

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Institutes: 5 from Asia, 6 from USA and 9 from Europe

A review of the milestones will be done at the coming LC workshop in October 2010 at Geneva.

R&D plan for e+ studies “ILC-CLIC e+ generation” working group

Important reduction of resources have registered in several institutes.

Therefore the ILC/CLIC work plan is reviewed according to the available resources from the different institutes around the world and the

possible contributions are presented.

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S. Dabagov

Channeling of charged particles

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Simulations for hybrid sources

Crystal target

Amorphous target

e- Photons

e+

O. Dadoun

=> will be included into G4and X. Artru simulation

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Channeling simulations

O. DadounComparison of 2 codes

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• CLIC: incident beam: 5 Gev; t1=1.4 mm; t2=10 mm

• ACCEPTED POSITRON YIELD• * For an incident e- beam with = 1 mm => 1 e+/e-• * For an incident e- beam with = 2.5 mm => = 0.9 e+/e-

• PEDD (Peak Energy Deposition Density) • Assuming an incident e- pulse of 2.34 1012 e-, we have :• CRYSTAL AMORPHOUS• PEDD/e- PEDD/total PEDD/e- PEDD/total• (GeV/cm3/e-) J/g (GeV/cm3/e-) J/g

mm 2 38 2.5 48.5 =2.5mm 0.35 6.8 0.8 15.5

• An entirely amorphous target, 9 mm thick, with the same incident e- beam would have provided the same accepted yield and a PEDD of 150 J/g (=1mm) or 40J/g (=2.5 mm). This shows the advantages of an hybrid scheme leading to a unique target with a PEDD < 35 J/g using an e- beam with = 2.5 mm.

Hybrid source advantage R. Chehab

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S

cm

N. e+

Yield

e+/e-

x mm mrad

y

mm mrad

<E> MeV

E

MeV

z

mm

z

cm MeV

4348 4204 0.70 7685 8105 2825.4 126.3 5.4 61.6

e+ in PDR: 2720; Yield e+/e- =0.453

A. Vivoli

CLIC Injector Linac

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Set up SiteLooking up from Down stream

KEKB Linac Tests for e+ production from hybrid targets

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Zoom on e+ crystal target

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hybrid

on axishybrid

off axis

conventional

8mm

conventional

18mm

3.4 enhancement

e+ yield (ADC counts)

black: 1mm W crystal

+ 8mm W amorphous

e+ yield at KEKB LinacExperimental results from hybrid targets T. Takahashi

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Why Compton scheme ?

1) Method to obtain polarized e+ (up to 90%)

2) Dedicated low energy e- beam (no inter-system dependence)

3) No issue for low energy scan operation

4) Technology feasibility can be evaluated before final construction

BUT still some difficulties:

1) Laser ( high power and high quality)

2) Optical cavity

3) Electrons: Ring-based, ERL-based, Linac-based Compton scheme

4) Positron stacking required

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Optimal Compton ringE. Bulyak

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F. Zomer

Optical cavity with 4 mirrors

For polarized e+ Compton source at ATF/KEK

Cavity arrived yesterday at Narita

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I. Chaikovska

Compton with multiple IP

Characteristics for simulations of polarized gammas source

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I. Chaikovska

Results for e+ production

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SR 1 47 m

e+ PDR

ERL32 ns

50 Hz

400 m

25 Hz

0.5 ns

312 bunches / train

1 train / ring

312 bunches spaced by 0.5 ns => 155.5 ns / turn

Stack in the same bucket every 69th turn

Number of stacking in the same bucket 1864

69 x 1864 = 128 617 turns

128 617 x 155.5 ns = 20 ms

SR 2 47 m

new CLIC scheme

Based on 2 CLIC stacking rings option F. Zimmermann

e+ stacking simulations

CLIC stacking rings must have much shorter damping times ~50 s and higher RF voltage (35 MV) than SLC damping rings

Large off-momentum dynamic aperture up to inj~9% (!) is also required

Preliminary simulations with semi-optimized parameters indicate >95% stacking efficiency

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Linac-based Compton scheme

Conventional Non-Polarized Positrons:

3-atmCO2 amplifier

parabolic mirrors

vacuum cell

detector

YAG (14 ps)200 ns

200 ps

Ge

3% over 1 s

First tests of the laser cavity:

Polarized -ray beam is generated in the Compton back scattering inside optical cavity of CO2 laser beam and 6 GeV e-beam produced by linac.

Laser cavity needs R&D.

6GeV e- beam 60MeV

beam 30MeV

e+ beam

to e+ conv. target

~2 m

V. Yakimenko

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ILC CLIC SuperB

Required e+/sec 3 1014 1.2 1014 3.2 1011

Required beam format 2856@5Hz 354@50Hz

1600@5min

Source beam format 286@50Hz 50@50Hz

Required e+ /bunch 3nC/2 1010 1nC/6 109 20pC/1.2 108

e- beam energy 6 – 4 GeV

beam peak energy 60 - 30 MeV

Ne+/N capture 2% (4%)

e- bunch charge 15(7.5)nC 5nC 1nC

bunch length (laser&e- beams)

3 ps

Number of laser IPS 10 10(5) 1

Total N/Ne- yield (in all IPs) 10 10(5) 1

Ne+/Ne- yield 0.2 0.2 0.02

# of stacking No stacking

V. Yakimenko

Compton Linac e+ sources

Proposed parameters are in black, Optimistic numbers are in Red

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•There is no funding for ATF to work directly for ILC, CLIC or SuperB:

•development of CO2 regenerative cavity, •high repetition rate operations

•There is an active program to use highest Compton X ray peak flux for single shot user experiments:

•Started with High efficiency conversion ~1x ray / 1 electron, Spatial distribution of second harmonic (U. Tokyo, KEK)

•Phase contrast imaging (INFN)•Diffraction scattering on the crystal (UCLA)

•There is an active CO2 development program at ATF

•required for ILC pulse parameters and amplifier bandwidth is demonstrated

•Gradual increase of the single pulse intensity is the main goal.

V. Yakimenko

Summary from BNL

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1) Higher harmonics are important and can influence the overall polarization.

2) Polarization and yields are always conflicting, compromises need to be made.

3) Lower energy drive beam (150 GeV) is more practical in achieving high degree polarization than higher drive beam energy (250 GeV).

W. Gai

Summary from ANL

Polarization issues with undulator based e+ source

Undulator 100 m long and drive beam energy 150 GeV

Collimator distance = 700 m Collimator iris = 2.5 mm

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Shock wave on BN windowT. OmoriExperiment performed at KEKB

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Summary from KEKT. Omori

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1) Review e+ sources of colliders

2) “ILC-CLIC e+ generation” working group Set new milestones

3) Hybrid and channeling e+ sources Review design progress for CLIC baseline source Review R&D status and set next goals

4) Compton Review R&D status and design progress Review the industrial, medical, material applications

5) Undulator Review R&D status and design progress Prepare re-baseline for ILC baseline source

6) Liquid Pb and Pure Conventional e+ sources Review R&D status and set next goals

Workshop achievements

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ILC NewsLine Report

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Apologizes for the talks which have not been mentioned in this Summary

http://atfweb.kek.jp/posipol/2010/index.htmlAll talks from the following link:

POSIPOL 2011

POSIPOL 2012 at Hamburg hosted by DESY

Conclusion

at Beijing hosted by IHEP

posipol workshop 2010

Documents