30.11.20121

Status MAMI facility

KHUK-workshop , 30.11. 2012 Kurt Aulenbacher

Institut für Kernphysik Uni Mainz

30.11.20122

Outline

• SFB 1044 and the operation of MAMI• Prisma and erection of MESA

30.11.20123

MAMI at IKP Mainz

1.6 GeV c.w. polarized beam150kW beam power

30.11.20124

Operation statistics 2005 – Nov. 2012

HD

SM

-opera

tion

46%

61% 72%

40%

51%

MAMI total (1991 – 2012): 129592 hours of operation

average availability for users: 85% !

36%

1%

30.11.20125

MAMI at IKP Mainz

Operational highlights 2012:-A4- ”experiment PV e-scattering on deuterium@200MeV

- KAOS chicane in high intensity operation

30.11.20126

MAMI beam time in 2012 (until November)Distribution between the experimental groups

Operation for experiments of SFB 1044 will continue for (hopefully) many years

30.11.20127

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

30.11.20128

MESA-hall-2

MESA-hall-1

MAMI/MESAseparation (shielding)

Experimentalhall

High power beam dump

Access- shaft

MESA at IKP Mainz

-no new buildings -MAMI experiments continue seperatly

30.11.20129

MESA acceleratorproject 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 (100-200MeV) 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 (Q2=0.005GeV/c at 30 degree). L>1039 cm-2s-1

2.) ERL-mode: 10mA at 100 MeV with L~1035 cm-2s-1

30.11.201210

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 EBPIT: 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~1039) ERL-mode: 10mA, 100 MeV unpolarized beam (Pseudo-Internal Hydrogen Gas target, L~1035)

DU

IN

SCPIT

RC

MESA-LAYOUT

to PV-experiment

PS

Existing walls: 2-3m thick shielding

MESA-Scheme

Area:22*14m2

1 2 3

2ERL

30.11.201211

Accelerator Layout

Design by Ralf Eichhorn (Deutscher Designpreis für Magnethochregallager)

Alternative: Double axis acceleration a la CEBAF: more compact, but less flexible!

30.11.201212

Accelerator Layout

P2

PIT

V. Bechthold/R. Heine

19.09.201213

ERL-PIT-experiments

Dublett

6mm dia

Dublett

H2

20 beam envelopefor n=5m

Pump

beam in

Assuming target density N=2*1018 atoms/cm-2 (3.2 g/cm2, 5*10-8 X0)we have (at I0=10-2 A) luminosity of L= I0/e*N=1.2*1035cm-2s-1

(average) ionization Energy loss: ~ 17eV RMS scattering-angle (multiple Coulomb scattering): 10rad 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

19.09.201214

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

30.11.201215

MESA-beam-parameters stage1/stage-2

Beam Energy ERL/EB [MeV] 105/155 (105/205)

Operating mode 1300 MHz, c.w.

Source type Photosource 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 recirculations 2 (3)

Beam power at exp. ERL/EB [kW] 100/22.5 (1000/30)

Total R.f.-power installed [kW] 120 (160)

30.11.201216

MESA- stage1 Timescale

Accelerator basic design: end 2013 Early 2014: ordering SRF

Early 2016 deliveryEnd 2017 operation

…Thank you!

30.11.201217

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 PHOM~I2

B

30.11.201218

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??

30.11.201219

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

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

INGRP CBP HCIDU

SC

RC

2m, 2MeV at PHF=30kW

5MeV

30.11.201220

Back-ups

30.11.201221

Spin polarized source layout

GUN /2●

Ө/2 varDSP

●

graded-Chop.550keV

Injection of 550kV high charge source

buncher

3m

2.5mSpin 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! Afalse <0.2ppb

30.11.201222

Spin rotation and source beam energy

V. Tioukine, K.A. NIM A 568 537 (2006)

ELme

Spin 2

11

100kV Filter, L=0.3m operated at 23kV over 2cm gapnot 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,

30.11.201223

Accelerator Layout

First Order beam optics for arcs, mergers & combiners

arcs

merger

30.11.201224

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

30.11.201225

Backups

30.11.201226

WHY is source-emittance so important for ERL-experiments?

6mm dia

Dublett Dublett

H2 20 beam envelope

Pump

length of Meters 2over mm62.0diameter beam Maximum

1:choose ))/(1(*)(

*)()(

0z*point symmetry aroundregion free field in the

)(*)(r

:function optical offunction a asdiameter Beam

50nm.~(100MeV) 1

goal)(MESA c)m*mrad*mm 3.2(or 10

*2**2

2

Geo2

NormGeo

eNorm

beam

mzz

zzz

zz

m

Geo

30.11.201227

Emittance requiments

An normalized emittance of 5 m is the key for successful operation of DM-experimentWith tbunch << taccel we have a lower limit for emittance at the cathode

GaAs)-(NEA1.0 (KCsSb), 4.0~)(

/1@7.7@2.0~6

)(2

0min

eVeVWE

mMVpCmmcE

WEq

cath

bunch

But: vacuum space charge destroys beam emittance…

Countermeasures: 1.) accelerate with high field to relativistic velocities because Fq~1/2. a) ERL-d.c guns ~3-6MV/m to 0.25-0.5 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 13 010101 (2010)) +350keV electrostatic Postaccelerator (reduced Version of famous 2MeV d.c.-MAMI-A injector)

30.11.201228

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)

30.11.201229

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!

30.11.201230

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) 30kW@200 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

30.11.201231

405nm 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

collimationtube

2cm€100 purchase from eBay

Diploma thesis I. Alexander

30.11.201232

Lifetime issue

• long lifetime required KCsSb (unpolarized) photocathode• lifetime about 100 hours @25mA demonstrated recently at Cornell

GaAs operation would be possible, but inconvenient

Milliampere- test experiment with NEA-GaAs

30.11.201233

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?)

30.11.201234

DM: Focusing through the PIT

length of Meters 2over mm62.0diameter beam Maximum

1:choose ))/(1(*)(

*)()(

0z*point symmetry aroundregion free field in the

)(*)(r

:function optical offunction a asdiameter Beam

50nm.~(100MeV) 1

goal)(MESA c)m*mrad*mm 3.2(or 10

*2**2

2

Geo2

NormGeo

eNorm

beam

mzz

zzz

zz

m

Geo

30.11.201235

DM: Focusing through the PIT

6mm dia

Dublett Dublett

H2 20 beam envelope

Assuming target density N=2*1018 atoms/cm-2 (3.2 g/cm2, 5*10-8 X0)we have (at I0=10-2 A) luminosity of L= I0/e*N=1.2*1035cm-2s-1

(average) ionization Energy loss: ~ 17eV could allow to recuperate more energy than in conventional ERL (2.5MeV). RMS scattering-angle (multiple Coulomb scattering): 10rad 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

E0=104MeV

Pump

30.11.201236

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, 50A at 14MeV(J. Tisler et al. ACS NANO 3,7 p.1959 (2009))

G. Werth et al. :Appl. Phys. A 3359 (1984)

MESA can produce ~109 positrons/s in a beam of <1cm diameter at 120eVsurface science: magnetic structures positronium production