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

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

The positron enthusiasts S. Riemann POSIPOL 2016 Summary

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

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) S. Riemann POSIPOL 2016 Summary

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 S. Riemann POSIPOL 2016 Summary

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

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 S. Riemann POSIPOL 2016 Summary

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 S. Riemann POSIPOL 2016 Summary

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 Go to "View | Header and Footer" to add your organization, sponsor, meeting name here; then, click "Apply to All"

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

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) S. Riemann POSIPOL 2016 Summary

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

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 S. Riemann POSIPOL 2016 Summary

T. Omori S. Riemann POSIPOL 2016 Summary

T. Omori S. Riemann POSIPOL 2016 Summary

T. Omori S. Riemann POSIPOL 2016 Summary

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

CLIC S. Doebert Preparation phase 2016-19 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 S. Riemann

CLIC parameters S. Doebert POSIPOL 2016 Summary S. Riemann

SuperKEKB e+ source SuperKEKB T.Kamitani POSIPOL 2016 Summary S. Riemann POSIPOL 2016 Summary

T.Kamitani S. Riemann POSIPOL 2016 Summary

After Posipol2015: T.Kamitani S. Riemann POSIPOL 2016 Summary

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

Production of Highly Polarized Positrons from MeV Polarized Electrons (PEPPo) E. Voutier http://wiki.jlab.org/pwg 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 % S. Riemann POSIPOL 2016 Summary

Rodin/Guler Hybrid sources S. Riemann POSIPOL 2016 Summary

Rodin/Guler S. Riemann POSIPOL 2016 Summary

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

The Gamma Factory Initiative M.W.Krasny X ray factories: energy up to ~100keV Intense g-rays (100-400MeV) would need ~TeV e- beams Simple idea: replace e- beam by a partially stripped ion (PSI) beam S. Riemann POSIPOL 2016 Summary

The Gamma Factory Initiative M.W.Krasny S. Riemann POSIPOL 2016 Summary

S. Riemann POSIPOL 2016 Summary

S. Riemann POSIPOL 2016 Summary