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30.11.2012 1 Status MAMI facility KHUK-workshop, 30.11. 2012 Kurt Aulenbacher Institut für Kernphysik Uni Mainz.

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Presentation on theme: "30.11.2012 1 Status MAMI facility KHUK-workshop, 30.11. 2012 Kurt Aulenbacher Institut für Kernphysik Uni Mainz."— Presentation transcript:

1 Status MAMI facility KHUK-workshop, Kurt Aulenbacher Institut für Kernphysik Uni Mainz

2 Outline SFB 1044 and the operation of MAMI Prisma and erection of MESA

3 MAMI at IKP Mainz 1.6 GeV c.w. polarized beam 150kW beam power

4 Operation statistics 2005 – Nov HDSM-operation 46% 61% 72% 40% 51% MAMI total (1991 – 2012): hours of operation average availability for users: 85% ! 36% 1%

5 MAMI at IKP Mainz Operational highlights 2012: -A4- ”experiment PV e-scattering on - KAOS chicane in high intensity operation

6 MAMI beam time in 2012 (until November) Distribution between the experimental groups Operation for experiments of SFB 1044 will continue for (hopefully) many years

7 PRISMA 15 June 2012: PRISMA excellence cluster is awarded to JGU  PRISMA includes construction of innovative particle acclerator for hadron/particle physics experiments in the 100 MeV range Mainz Energy recovering Superconducting Accelerator

8 MESA-hall-2 MESA-hall-1 MAMI/MESA separation (shielding) Experimental hall High power beam dump Access- shaft MESA at IKP Mainz -no new buildings -MAMI experiments continue seperatly

9 MESA accelerator project rationale 1.Energy recovery linac (ERL) 2. Recent progress in high gradient-c.w.-SRF Experiments conceivable which require a new & innovative accelerator low energy ( MeV)  therefore accelerator ‘affordable’ MAMI acc. team competence represents basis for development Project will be attractive for young students and researchers Make use of innovations in SRF accelerator science: Beam parameter goals in two different modes of operation: 1.) EB-mode External spin-polarized c.w. beam at 200 MeV (Q 2 =0.005GeV/c at 30 degree). L>10 39 cm -2 s -1 2.) ERL-mode: 10mA at 100 MeV with L~10 35 cm -2 s -1

10 KEY: PS: Photosources: 100keV polarized (EB, ERL (low charge)), 500keV unpolarized (ERL, high charge) IN: 5 MeV – NC injector SC: 4 Superconducting cavities Energy gain 50 MeV per pass. 1-3 Beam recirculations for EB Orbit 1 common to ERL and EB, Orbit 2 could be separate for ERL and EB PIT: Pseudo Internal target (ER-experiment) PV: Parity violation experiment (EB-mode) DU: 5 MeV beam dump in ERL-mode EXPERIMENTAL BEAM PARAMETERS: 1.3 GHz c.w. EB-mode: 150  A, 200 MeV polarized beam (liquid Hydrogen target L~10 39 ) ERL-mode: 10mA, 100 MeV unpolarized beam (Pseudo-Internal Hydrogen Gas target, L~10 35 ) DU IN SC PIT RC MESA-LAYOUT to PV-experiment PS Existing walls: 2-3m thick shielding MESA-Scheme Area:22*14m ERL

11 Accelerator Layout Design by Ralf Eichhorn (Deutscher Designpreis für Magnethochregallager) Alternative: Double axis acceleration a la CEBAF: more compact, but less flexible!

12 Accelerator Layout P2 PIT V. Bechthold/R. Heine

13 ERL-PIT-experiments Dublett 6mm dia Dublett H2H2 20  beam envelope for  n =5  m Pump beam in Assuming target density N=2*10 18 atoms/cm -2 (3.2  g/cm 2, 5*10 -8 X 0 ) we have (at I 0 =10 -2 A) luminosity of L= I 0 /e*N=1.2*10 35 cm -2 s -1  (average) ionization Energy loss: ~ 17eV  RMS scattering-angle (multiple Coulomb scattering): 10  rad  single pass beam deterioration is acceptable Note: storage ring: beam emittance lifetime ~ 10milliseconds (stationary vs. variable background…)  beam halo & long tails of distribution due to Coulomb scattering have to be studied V. Tioukine

14 EB workhorse experiment : PVES at low Q (P2 experiment within SFB 1044)

15 MESA-beam-parameters stage1/stage-2 Beam Energy ERL/EB [MeV]105/155 (105/205) Operating mode1300 MHz, c.w. Source typePhotosource d.c. 100keV, polarized (additional source 200keV, non- polarized) Bunch charge EB/ERL [pC]0.15/0.77 (0.15/7.7) Norm. Emittance EB/ERL [  m] 0.2/<1 (0.2/<1) Beam polarization (EB-mode only)> 0.85 Beam recirculations2 (3) Beam power at exp. ERL/EB [kW]100/22.5 (1000/30) Total R.f.-power installed [kW]120 (160)

16 MESA- stage1 Timescale Accelerator basic design: end 2013 Early 2014: ordering SRF Early 2016 delivery End 2017 operation …Thank you!

17 SRF-main accelerator issues 9 cell ‘TESLA’ (E-XFEL)  -mode structure: Q-curve often measured under not realistic ‘vertical’ conditions…esp. dust particles & contamination films may appear during horizontal assembly, accidents in the vacuum system, etc…. New HIM-building Mainz: is planned to be equipped with a Clean room facility & high pressure (ultrapure) water rinsing (HPR) Problem for high c.w. current operation: HOM excitation P HOM ~I 2 B

18 A REAL SRF ‘module’ True c.w.-operation SRF facilities: CEBAF, ELBE, S-DALINAC (3GHz) not: E-XFEL, FLASH, TESLA/ILC. c.w. requires lowering the Gradient due to power dissipation! J. Teichert et al. NIMA 557 (2006) 239 Such modules can be ordered from industry. Missing: sufficient higher order mode damping for I>2-4 mA. Note MESA stage-2 ERL-current is 40mA!  modify after stage-1 or take the risk??

19 Injector issues Pro‘s for normal conducting injector: no cryogenic load considerably lower cost, established design, e.g. >9mA c.w. without BBU (HOM excitation strongly suppressed) high flexibility: variable beta-design is feasible!  probably better beam quality than existing SRF injectors GRP: Gun/rotator/ polarimeter (EB-mode) CBP: Chopper/buncher Preacc. (g-beta) HCI: 511keV high bunch charge injection (ERL-mode, stage-2) PV IN GRP CBPHCI DU SC RC 2m, 2MeV at P HF =30kW 5MeV

20 Back-ups

21 Spin polarized source layout GUN  /2 ● Ө  /2  var DSP ● graded-  Chop. 550keV Injection of 550kV high charge source buncher 3m 2.5m Spin rotation axis Spin direction to second part Systematic electron optical helicity reversal! (similar to JLAB/QWEAK)  tension with desire to have a SHORT injection for high charge  separate 550kV gun from first part strongly influenced by need of ‘false’ asymmetry control! A false <0.2ppb

22 Spin rotation and source beam energy V. Tioukine, K.A. NIM A (2006) 100kV Filter, L=0.3m operated at 23kV over 2cm gap  not practical to handle filter at 500keV (  =2), … but could probably work at 200keV (200keV source is able to reach emittance goal at 7.7pC!) JLAB development: A 200keV source is nowadays very compact - R. Suleiman et al. Proceedings ERL2011,

23 Accelerator Layout First Order beam optics for arcs, mergers & combiners arcs merger

24 Summary/Outlook MESA: First ERL with particle physics experiments in Europe Detailled considerations have begun for all subsystems Superconducting Radiofrequency System and it‘s cryogenics is main cost driver. MESA funding is part of ‚PRISMA‘ excellence cluster req ERL operation restricted so far to 1mA in order to save costs for development and cryogenics of high current SRF sections (additional ~ 5 M€) Great support from TU-Darmstadt, hope to continue collaboration Mainz also collaborates with HZB (Berlin-Pro) &CERN (LHeC) Photoinjectors collaborations with HZD (ELBE) and HZB main issue now, after funding decision: creating a powerful team! good reason to believe that stage-1 can be made operational within 5 years

25 Backups

26 WHY is source-emittance so important for ERL-experiments? 6mm dia Dublett H2H2 20  beam envelope Pump

27 Emittance requiments An normalized emittance of  5  m is the key for successful operation of DM-experiment With t bunch << t accel we have a lower limit for emittance at the cathode But: vacuum space charge destroys beam emittance… Countermeasures: 1.) accelerate with high field to relativistic velocities because F q ~1/  2. a) ERL-d.c guns ~3-6MV/m to MeV b) SRF gun with 15MV/m to ~ 5 MeV (FZD, future: BERLinPRO).  MESA –baseline for ERL-source: 200keV ‘inverted‘ Photogun a la JLAB (P. A. Adderley et al. PR-ST-AB (2010))  +350keV electrostatic Postaccelerator (reduced Version of famous 2MeV d.c.-MAMI-A injector)

28 SRF-main accelerator issues 9 cell ‘TESLA’ (E-XFEL)  -mode structure: Q-curve often measured under not realistic ‘vertical’ conditions…esp. dust particles & contamination films may appear during horizontal assembly, accidents in the vacuum system, etc…. New HIM-building Mainz: is planned to be equipped with a Clean room facility & high pressure (ultrapure) water rinsing (HPR)

29 A REAL SRF ‘module’ True c.w.-operation SRF facilities: CEBAF, ELBE, S-DALINAC (3GHz) not: E-XFEL, FLASH, TESLA/ILC. c.w. requires lowering the Gradient due to power dissipation! J. Teichert et al. NIMA 557 (2006) 239 Such modules can be ordered from industry. Missing: sufficient higher order mode damping for I>2-4 mA. Note MESA ERL-current is 40mA!

30 Recirculator 200 MeV EB could require vertical stacking of 3fold recirculation Merger Systems complicated due to limited space But Magnets very small (compared to MAMI) Beam power (EB) MeV (ERL) 50kW at 5MeV  R.f power needed EB ~ 120kW ERL ~ 140kW 1300 MHz R.f. supplied by reliable & stable semiconductor amplifiers (not Klystrons!) Experiments are TINY Dark photon-exp. PV-Experiment 14m

31 nm Laser Advantage of 405 nm: KCsSb QE~30mA/Watt. Cost ~ 3k€/watt (d.c.); optimum beam quality: 1mm dia-spot at 1m only with collimation tube! electron gun current presently limited by power supply (<3mA) Diode is well suited for pulsing at GHz-frequencies, (<40ps at full power) Could provide ~1W (40ps, r.f. synchronized) for MESA (1 lifetime ‘overhead’)  five DVD-player diodes in parallel! d.c or R.f Laser-out collimation tube 2cm €100 purchase from eBay Diploma thesis I. Alexander

32 Lifetime issue long lifetime required  KCsSb (unpolarized) photocathode lifetime about 100 demonstrated recently at Cornell GaAs operation would be possible, but inconvenient Milliampere- test experiment with NEA-GaAs

33 PCA fabrication chamber at Mainz-HIM : PCA-Apparatus KCsSb technology available at Mainz good results >30mA/Watt (>10% Q.E) evidence for *100 stability increase with respect to GaAs (2000 hours at 10mA?)

34 DM: Focusing through the PIT

35 DM: Focusing through the PIT 6mm dia Dublett H2H2 20  beam envelope Assuming target density N=2*10 18 atoms/cm -2 (3.2  g/cm 2, 5*10 -8 X 0 ) we have (at I 0 =10 -2 A) luminosity of L= I 0 /e*N=1.2*10 35 cm -2 s -1  (average) ionization Energy loss: ~ 17eV  could allow to recuperate more energy than in conventional ERL (2.5MeV).  RMS scattering-angle (multiple Coulomb scattering): 10  rad  single pass beam deterioration is acceptable Note: storage ring: beam emittance lifetime ~ 10milliseconds (stationary vs. variable background…)  beam halo & long tails of distribution due to Coulomb scattering have to be studied E 0 =104MeV Pump

36 MESA-experiments-3: Applied physics High beam power electron beam may be used for: ERL-mode: Production of NV-nanodiamonds (e.g. medical markers) EB-mode: High brightness source of cold (polarized) positrons Color: NV-centers introduced in Diamond. Irradiated at MAMI for 3 days, 50  A at 14MeV (J. Tisler et al. ACS NANO 3,7 p.1959 (2009)) G. Werth et al. : Appl. Phys. A (1984)  MESA can produce ~10 9 positrons/s in a beam of <1cm diameter at 120eV  surface science: magnetic structures  positronium production


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