WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN

Progress and challenges of the PSI Meson targets and relevant systems

Daniela Kiselev :: Department head ASA :: Paul Scherrer InstitutP. Baumann, P. Duperrex, S. Jollet, A. Knecht, D. Laube, C. Nyfeler, D. Reggiani, R. Sobbia, V. Talanov, M. Wohlmuther

The 3rd J-PARC Symposium (J-PARC2019)September 23-26, 2019, Tsukuba, Japan

Accelerator Facilities at PSI

p-Therapy250MeV, <1µA

Swiss Light Source2.4GeV, 400mA

High Intensity Proton Accelerator590 MeV, max. 2.4mA

SWISSFEL 5.8 GeV

Central control room

SINQ Spallation Neutron SourceUCN

The PSI Proton Accelerator Facilities

HIPA (High Intensity Proton Accelerator)- CW (50.63 MHz), 590 MeV, - up to 2.4 mA(1.44 MW) - 2 meson production targets - 7 secondary beam lines- SINQ and UCN spallation source

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PROSCAN (Proton therapy): since 2007Comet: superconducting cyclotronCW, 250 MeV, up to 1 µA protonsmedical treatment:3 Gantries, 1 Eye Cancer Treatment StationIrradiation Station: PIF

PIF

SecondaryBeam Lines

hot cell HIPA

Gantry 1, 2 3Target M

Comet

Target E

Spallation neutron source SINQ

Injector II

Injector IECR-source &Cockroft-Walton

OPTIS

Ring

UCN

μ/π Secondary Beam Lines

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Target E

p-Beam Spin rotator

πE1

μE1μE4

πM1

πM3

πE5

Target M

πE3

Target M:πM1: 100-500 MeV/c PionsπM3: 28 MeV/c Surface Muons

Target E:πE1: 10 - 500 MeV/c High Intensity Pions und MuonsμE1: Polarized Muon BeamπE3: 28MeV/c Surface polarized MuonsμE4: 30 - 100 MeV/c High Intensity Polarized MuonsπE5: 10 - 120 MeV/c High Intensity Muons

Challenges for meson production targets

• Power deposition: at 2.4 mA, 590 MeV protons ~ 50 kW on Target E cooling high temperature resistant material thermal stress

• Radiation damage: embrittlement deformation (also due to heating) loss of conductivity

Approach:• distribute power:

rotating wheel with 1 Hz needs bearings• cooling by radiation:

- independent of conductivity- local shielding (Cu) is cooled by water

p-beam

Target E

Drive shaft Motor

• Motor: 2.5 m above the beam lineFunctioning is not affected by irradiation life time ~ 5 – 8 years

Targetwheel

Watercooling

Localshielding

deep grooveball bearings

angular contactball bearings

140 oC

50 oC

Challenges for meson production targets

• Wheel deformation reduced by- polycrystalline graphite isotropic properties- slits in wheel rim für thermal expansion

- spokes: allows thermal expansion of target conehollow to avoid high temperature at bearing

12 segments with 1 mm slit

1700 K

Critical components: Bearings

No grease as lubrication! brittle due to hard irradiationso called radiation hard grease does not help proofed

Balls Si3N4, GMN, GermanyCoating: MoS2, Ag for ring & cage1 -2 x exchange/year Graphite wheel lasts muchlonger: ~ 4Years (39 Ah record)

• Ball bearings:

in use:

Shun Makimura(JPARC)

in test:

Balls stainless steel + WS2 blocks Koyo, JapanTest (without radiation): > 420 daysTest in beam at PSI planned next year

Monitoring of the motor currentcu

rren

t[A

]

0

1

2

3

4

5

averagemotor current

new bearing

Targ

et E

Exc

hang

e

peakmotor current

rotation/min

beam current

Extraction of Target E insert

Exchange flask: − 45 t, shielded with 40 cm steel− remotely operated

Working platform:− ~ 2m above beamline, shielded with steel− Accessible after removing 3 – 4 m of concrete

"Bridge":− contains contamination protection− door to close lifting hole− sticks for positioning of the flask

Transport of 2. target insert to beamline

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open closedparking lot

sluice to hotcell

To save time:Spare Target E insert is taken out from the parking lot

Exchange flask on parking lot

At the same time:Reparing of the insert from beamline in hotcell

Transport to hotcell PSI West (ATEC)

Exchange of bearings with manipulatorView into hotcell of ATEC

Hub

− Remote handling necessary: up to 3 Sv/h− Handing over from flask to hotcell via sluice

Usually only the hub needs to be exchanged not much radioactive waste (up to 200 mSv/h)

Design of the hotcell ATEC

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ATEC: 2. service cell in 2019− wall in between can be opened vertically

Advantage:− in case of unavoidable access to one service cell (in case of failure),

radioactive components are moved to the other service cell.− less personal dose rate during cleaning:

drums with rad. waste can be moved temporarly to the other service cell.

2. Service cell 1. Service cell

Sluice in between Sluice for Target E

Room for personal

Sluice pulled up by external crane

Moved byATEC crane

Standard equipment of hotcell ATEC

6 high-resolution cameras/service cell

1 power manipulator/service cell

"cold" handin control room

"hot" handin service cell

for wall shielding

+ 1 leadglass window+ 1 dosimeter+ a trolley to move things around

(up to 60 t)+ 1 crane/cellmovable over 2 service cells(important, if 1 crane fails)

Gripfor camera

Target E93 in April 2012: 33.5 Ah ~ 3.5 years

Tilt of the segments observed! Quantitative measurement

of tilt in hot cell (ATEC) Displacement up to -2 mm Shrinking of about 1% at 39Ah likely due to radiationWhy only E93?

A closer look to the target E93 after irradiation

Target development I: Target E with grooves

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Grooves inside and outside − with different frequencies:

114 Hz and 138 Hz− to distinguish beam left and right

from center− different depths:

0.3mm, 0.5mm, 0.7mm, 0.9mm− to find comprommise between

losses and signal

Purpose: Beam centering on the 6 mm rim of Target E

Idea:Modulation of the beam current measurement (MHC5) after Target E Strength of the signal is a measure for the deviation of the beam from center

Modulation of beam current at 0.75 mA after Tg E

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1 1.5 2 2.5

time [sec.]

-0.01

0

0.01

[mA]

AC part of the beam intensity monitor MHC5 raw signal

1 1.5 2 2.5

time [sec.]

-0.01

0

0.01

[mA]

MHC5 filtered signal

With Filter

Raw signal

1 s

1 Hz: period of the target wheel12 Hz: 12 Slits: broad due angle

Slits

Modulation due to grooves

Modulation due to grooves not seen by eye and effected by noise Frequency analysis (FFT) necessary

MH

C4*T

-MH

C4M

HC4

*T-M

HC4

MHC4: current before Target ET: transmission: for 60 mm target T = 0.6MHC5: current behind Target E

Signal as a function of position

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• Very sensitive method of ~factor 10 in signal change!• Much more sensitive than transmission T = MHC5/MHC4

59.1

59.15

59.2

59.25

59.3

59.35

Target

-E tran

smissi

on [%]

1.6 mA (MHC4)

-1.5 -1 -0.5 0 0.5 1 1.5

AHPos [mm]

0

1

2

3

4

5

6

7

Mod

ulat

ion

Ampl

itude

[a.u

.]

F=138Hz

F=114Hz

Deviation from center of Target E [mm]-1.5 -1 -0.5 0 0.5 1 1.5

Ampl

itude

ofm

odul

atio

n

7

6

5

4

3

2

1

0

114 Hz138 Hz

-1 -0.5 0 0.5 1

Tran

smiss

ion

59.1

59.2

59.3- Small change in

Transmission- Slower than

modulationanalysis

Target development II: Slanted Target E

Beam

Standard Target E Slanted Target E

effective 40 mmgraphite target Geant4 simulation:

30 – 60 % forsurface muon production(A. Papa talk)

40 m

m

Proton beam

100

mm

oCAnsys simulation:

More thermal stress due to inhomogeneoustemperature distribution Deformation??

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Test with slanted type target out of Aluminum

Test of slanted type target

Test End of November 2019 in Target E vacuum chamber

Slanted target:very tight!

Needs to be tested first!

on bothtargetinserts

There should be 8 – 10 mm space

in parking slot= same dimensionsthan in beamline

Target-M

P-BEAM

Target M:

Mean diameter: 320 mm

Target thickness: 5.2 mm

Target width: 20 mm

Graphite density: 1.8 g/cm3

Beam loss: 1.6 %

Power deposition: 2.4 kW/mA

Temperature: 1100 K

Irradiation damage: 0.1 dpa/Ah

Rotational Speed: 1 Hz

Current limit: 5 mA

Life time: up to several years

up to ~ 60 Ah ~ 6 DPA

.

Improved design(2013)

Target-M insert

Drive-motor

p

(old) Target M insert mounted on wheels

π, µ

π, µ

Design of the new Target-M insert (2012)

• improved vacuum flange: seal can be exchanged/cleaned• drive shaft: better heat protection for the bearings

1. part made from Ti-V ( instead of steel) to prevent heat conduction• additonal cooled Cu- plate better cooling and protection of bearings

against radiated heat

VacuumChamber

Graphite Wheel

TungstenCollimator

TemperatureSensors

Drive-Motor

Proton-Beam

Secondarybeamlines

CooledCu-plate

TiVshaft

Steel shaft

Future Project: High Intensity Muon Beam (HIMB)

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slanted 20 mm graphite wheel

2 solenoids close to target

Factor 100 more Muons

Many constraints due to present beamline Feasibility study will start soon

Present design:

Future design:

5 mm graphite

Talk A. Papa

Summary

• Introduction to the PSI High Intensity Proton Accelerator (HIPA)

• Extraction from the Ring Cyclotron

• Beam transfer to the meson production targets M/E and SINQ spallation source

• Beam diagnostics for setup & optimization

• Feasibility study of beam rotation for SINQ

• Beam switchover to the UCN source

• Conclusion

PSI Meson target facility M and E with several beamline: π, µ Bearings are critical for Target E For exchange infrastructure needed: exchange flask, hot cell New target designs: grooves for beam position diagnostics Slanted target for test and higher muon rates Target M: Ideas for increasing muon rate by factor 100 (HIMB project)

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PSI congratulates to 10 years of J-PARC