1. https://indico.lal.in2p3.fr/event/3288/
POSIPOL 2016
Short Summary
ILC project DESY
Sabine Riemann (DESY)
23. Sept 2016

2. What is POSIPOL ?? (Positrons polarisés)
Series of annual workshops focused on polarized positrons for Linear Colliders but not only ……
Discuss options and open issues of polarized positron source, based on laser Compton back scattering and undulator, for CLIC and ILC
Assess and coordinate the outstanding R&D efforts
Analyze the experimental programs carried out in the different laboratories
Application of Compton radiation source to the industrial and medical field
Program was extended also to unpolarized positron source
2006 to 2016: 10 years POSIPOL
S. Riemann
POSIPOL 2016 Summary

3. The positron enthusiasts
S. Riemann
POSIPOL 2016 Summary

4. Topics in 2016 POSIPOL from 2006 to 2016 L.Rinolfi (25 talks)
Compact X-ray source: ThomX (H.Monard)
The Gamma Factory Initiative (Mieczyslaw Witold Krasny)
Quantum effects in production of gammas for positrons (E.Bulyak)
Effects of correlated thermal vibrations of crystal atoms on bremsstrahlung and dechanneling (X.Artru)
Update on the hybrid positron source. (H.Guler, V. Rodin)
Freedback free optical cavity (T.Takahashi)
Fabry-Perot cavity R&D at Orsay (X.Liu)
SuperKEKB positron source status (T.Kamitani)
Status of the CLIC study and update on the CLIC positron source (S.Doebert)
Production of highly polarized positrons from MeV polarized electrons (E.Voutier)
+ ILC related talks
S. Riemann
POSIPOL 2016 Summary

5. ILC related talks (13 talks in 2016)
Requirements of running at low energies at Z-pole and W-threshold (G.Moortgat-Pick)
Central Region Group status and Positron Region (K.Yokoya)
undulator based source
Update of ILC positron source parameters (A.Ushakov)
First results for the ILC polarization from realistic undulator (K.S. Alharbi)
Status: Design of the ILC positron target cooled by thermal radiation (S.Riemann)
Thermomechanical examinations for the design of the radiation cooled positron target (F.Dietrich)
Target material tests with the electron beam at the microtron in Mainz (A.Ignatenko)
ILC Active sliding contact cooling Target R&D update (Wanming Liu)
electron driven source
A start to end simulation of electron driven positron source for ILC (M.Kuriki)
Energy deposition around the target of the electron driven positron source (T.Takahashi)
Target stress simulation (S.Jin)
Rotation target R&D of electron driven positron source (T. Omori)
Possible technical solutions of conventional and undulator targets (P. Sievers)
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POSIPOL 2016 Summary

6. Undulator based e+ source
Source parameters
Check & discussion – A. Ushakov
Realistic undulator spectrum (A. Alrashdi, K. Alharbi)
Target: 0.4 X0 Ti6Al4V, wheel Ø1m, 2000rpm (100m/s) in vacuum
Cooling by thermal radiation (DESY/Uni HH)
Cooling with sliding pads (ANL/Tsinghua)
Central region WG (Yokoya)
TDR 2012
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POSIPOL 2016 Summary

7. Realistic undulator spectrum
POSIPOL2015:
Realistic undulator B fields influence photon spectrum (Jenkins, Alrashdi)
2016
Goal: photon spectrum using realistic B fields based on the field measured in the undulator prototypes
Studies restarted recently (Ayash Alrashdi & Khaled Alharbi, KACST, Riyadh, Saudi Arabia); first result for 150GeV e- beam:
S. Riemann
POSIPOL 2016 Summary

8. Target cooling by thermal radiation
photons
Target cooling by thermal radiation
Ti6Al4V
Radiator (Cu)
Cooler (Cu)
DESY/U Hamburg/P. Sievers
Rotating target wheel consists of Ti rim (e+ target) and Cu (radiator)
Heat path:
thermal conduction Ti  Cu wheel
Thermal radiation of Cu to stationary water cooled coolers
Target, radiator and cooler are in vacuum
Felix Dietrich
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POSIPOL 2016 Summary

9. Radiative cooling - Design optimization
DESY/U Hamburg/Sievers
Radiative cooling - Design optimization
photons
problem: low heat conductivity in Ti rim  overheating must be avoided
Fatigue limit at elevated temperatures?
Heat contact Ti target rim to radiator?
Material parameter change under irradiation
 Study is ongoing
(DESY, Uni HH, Uni Mainz)
Ti6Al4V
Radiator
(rotating)
Cooler (stationary)
Felix Dietrich
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POSIPOL 2016 Summary

10. Full Size Target Wheel Ready for Operations in Vacuum
Active Sliding Contact Cooling Demo Conceptual Illustration
Overview
W. Liu
Rotating 1meter diameter Target Wheel at 2000 rpm (100 m/s) while extracting ~10kW by using active sliding contact cooling.
Target wheel is driven by a magnetically coupled drive motor which separates the motor from the vacuum.
Stability of wheel controlled by heavy duty machine spindle.
Temperature of wheel controlled by 4 Active Sliding Contact Cooling Pads.
Cooling Pad’s temperature controlled by water/coolant.
Heat applied to wheel using UHV radiant filament heaters.
Diagnostic feedback: RPM, Temp and Pressure of Cooling Pads, Temp of Target Wheel, Vibration, etc. 6 1 4 3 2
Full Size Target Wheel Ready for Operations in Vacuum
S. Riemann
POSIPOL 2016 Summary
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11. Target cooling with sliding pads
W. Liu
Summary of phase 1
The measured data clearly demonstrated that sliding contact cooling concept.
A rough estimate on the cooling capacity from different measurements is ranging from about 14W to 240W has indicated that we need better mechanical design on the cooling pads support system and there are still rooms for performance improvements on the cooling pads.
Phase 2 :
A fully functional prototype running at full speed over long periods of time in vacuum
Significant funding is required - currently not available
S. Riemann
POSIPOL 2016 Summary

12. Target material tests A. Ignatenko
Test cyclic load expected from photon beam at e+ target (and other components) using MAMI e- beam (BMBF project)
First results from run with 14MeV electrons:
Target #3 (2mm thick)
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POSIPOL 2016 Summary

13. Central region Main issues needed as inputs to CRWG
K. Yokoya
Main issues needed as inputs to CRWG
Design of photon dump
A problem (damage of the window by undulator photon beam) of TDR design pointed out at Santander
Required shielding of the target region including thoughts on
Target replacement
Where/how waste targets to be stored
Path to take waste target to the surface
Whole system must be reviewed
Installation
Commissioning
Accidents
Problem: need experts
S. Riemann
POSIPOL 2016 Summary

14. Truly conventional e+ source
T. Omori
Idea: stretch the load at the 4X0 WRe target to 63ms
Stress at SLC target and ILC target are comparable for target wheel Ø0.5m, 5m/s
Target wheel design R&D and prototyping
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POSIPOL 2016 Summary

15. T. Omori
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POSIPOL 2016 Summary

16. T. Omori
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POSIPOL 2016 Summary

17. T. Omori
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POSIPOL 2016 Summary

18. Truly conventional e+ source
Design R&D and prototyping (T.Omori)
Energy deposition and radiation aspects a=under study (T. Takahashi)
progress with an realistic geometry
dose estimates and shielding studies sill to be done
Positron Capture Simulation (M. Kuriki)
The positron yield for the conventional ILC positron source is evaluated by assuming a realistic RF unit and a realistic RF model.
S. Riemann
POSIPOL 2016 Summary

19. CLIC
S. Doebert
Preparation phase is well defined and in line with European Strategy
Prepared to align with LHC physics outcomes as results become available
Aim to provide optimized staged approach up to 3 TeV with costs and power not excessive compared with LHC, with an initial 380 GeV stage
Excellent progress key technology developments: X-band structures, high efficiency power source, two beam modules, drive beam components, permanent magnets, alignment
Successful performance verifications, drive beam (CTF3), main beam emittance conservation (FACET) and final focus studies (ATF)
Small effort in optimizing the positron source but with promising results factor 2 in positron yield at PDR might be possible
POSIPOL 2016 Summary
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20. CLIC parameters
S. Doebert
POSIPOL 2016 Summary
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21. SuperKEKB e+ source SuperKEKB T.Kamitani POSIPOL 2016 Summary
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POSIPOL 2016 Summary

22. T.Kamitani
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POSIPOL 2016 Summary

23. After Posipol2015:
T.Kamitani
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POSIPOL 2016 Summary

24. SuperKEKB - Summary
T.Kamitani
Flux concentrator (FC): work hardening process is important; test stand with new FC assembly #2 has been constructed
After finishing test operation, FC assembly #2 will be installed in beamline in 2017
Positron yield = 30% (Q(e+)=1.9nC/Q(e-)=6.3nC) stable injection in LER since Feb 2016
DR commissioning and LER injection in phase-2 will start in Oct 2017
S. Riemann
POSIPOL 2016 Summary

25. Production of Highly Polarized Positrons from MeV Polarized Electrons (PEPPo)
E. Voutier
Next steps:
Maximizing beam intensity and quality
Polarized e+ experimental program at JLab12 and JLEIC became realistically and is being developed
PEPPo demonstrated efficient polarization transfer from 8.2 MeV/c electrons to positrons, expanding polarized positron capabilities from GeV to MeV accelerators.
e- beam polarization
85.2 ± 0.6 ± 0.7 %
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POSIPOL 2016 Summary

26. Rodin/Guler
Hybrid sources
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POSIPOL 2016 Summary

27. Rodin/Guler
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POSIPOL 2016 Summary

28. ThomX - compact X ray source demonstrator
H.Monard
ThomX - compact X ray source demonstrator
ThomX = Compton source project for X rays, 40 ÷ 90 keV, in Orsay
Electrons collide with laser pulse accumulated in a Fabry- Perot resonator.
Final goal:
X-ray flux of 1013 ph/s.
Users:
especially in the area of medical science and cultural heritage
Technical challenges:
High mean laser power : 100W
Fabry-Perot cavity finess: 30000
Alignment at IP <50mm
User operation: spring 2018
S. Riemann
POSIPOL 2016 Summary

29. The Gamma Factory Initiative
M.W.Krasny
X ray factories: energy up to ~100keV
Intense g-rays ( MeV) would need ~TeV e- beams
Simple idea: replace e- beam by a partially stripped ion (PSI) beam
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POSIPOL 2016 Summary

30. The Gamma Factory Initiative
M.W.Krasny
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POSIPOL 2016 Summary

31. S. Riemann
POSIPOL 2016 Summary

32. S. Riemann
POSIPOL 2016 Summary