Commissioning of an in-vacuum undulator beam line optics ... · and direct gas-bremsstrahlung measurements. ... DCM diaphragm U20 Si111 M1 (V foc) UHV M2 (plan) ... –Back Wall :

RadSynch’09 – May 21-23 2009 Jean-Baptiste PRUVOST

Commissioning of an in-vacuum

undulator beam line optics hutch

and direct gas-bremsstrahlung

measurements

http://www.elettra.trieste.it/


CONTENTS

• Radiation safety commissioning of the first

optics hutch of SIXS beam line at SOLEIL– Brief present SOLEIL status

– Short description of the beamline

– Measurements set up

– Results & comparison with MC calculations (P. Berkvens)

– Cumulative Troubles

– Conclusion

• Direct gas-bremsstrahlung measurements– Radiation measurements results



SOLEIL present status

• SOLEIL accelerators consists on:– 100MeV LINAC, 3-8nC @ 3Hz (normal op.), 10Hz (tests)

– 156m circ. BOOSTER accelerating electrons up to 2.75GeV, 3Hz

– 354m SR for 500mA, top-up mode operations, ¾, 4/4, single or 8 bunches mode and hybrid filling patterns

– Now able to run up to 450mA and top-up mode, ~6h life time for machine operations

– 300mA and top-up mode since November 2008

• 20 BL already constructed, 2 more by the end of 2009– 11 phase I BL, 5BM(2IR) and 6ID

– 9 phase II BL, 3BM and 6ID

– 6 remaining phase II ID BL to be built, 2(1canted invacID) in 2009, 3(1 invacW) in 2010, 1(canted invacID) in 2011



SOLEIL present status

• SOLEIL accelerators consists on:– 100MeV LINAC, 3-8nC @ 3Hz (normal op.), 10Hz (tests)

– 156m circ. BOOSTER accelerating electrons up to 2.75GeV, 3Hz

– 354m SR for 500mA, top-up mode operations, ¾, 4/4, single or 8 bunches mode and hybrid filling patterns

– Now able to run up to 450mA and top-up mode, ~6h life time for machine operations

– 300mA and top-up mode since November 2008

• 20 BL already constructed, 2 more by the end of 2009– 11 phase I BL, 5BM(2IR) and 6ID

– 9 phase II BL, 3BM and 6ID

– 6 remaining phase II ID BL to be built, 2(1canted invacID) in 2009, 3(1 invacW) in 2010, 1(canted invacID) in 2011

16 operating with users in top-up mode @ 300mA

4 under commissioning



Brief SIXS beam line description

• Solid surfaces and interfaces structures

• Nanostructures

• Self-organised surfaces

• Original in-situ growth

• Surface magnetic X-ray diffraction

• Surface in catalytic environment

• Solid-liquid electrochemical interfaces

• Buried soft interface

• Liquid-liquid interfaces

U20diaphragmDCMSi111

M1(V foc)

UHV M2 (plan)

MEDM3(H foc)

M3 (H foc)

Phase plate device

Surface and Interface XSurface and Interface X--ray Scattering (SixS)ray Scattering (SixS)A. Coati, B. A. Coati, B. VoisinVoisin, M. , M. SauvageSauvage, Y. Garreau , Y. Garreau

GIXD, GISAXS, XRR, magnetic X-ray scattering, coherent scattering

UHV UHV facilityfacility Multi Multi EnvironmentEnvironment facilityfacility

RingOHEH1EH2

UHV Diffractometer

ME Diffractometer

BeamBeam characteristicscharacteristicsDimensions : ~ 50x120 m2 (FWHM)Divergence: ~ 600x60 rad2

Dimensions : ~ 60x60 m2 (FWHM)Divergence: ~ 600x120 rad2

Open to users

in 2010

ScientificScientific CaseCase

Flux Flux 4 1013 ph/s with E/E ~ 10-4 (6 keV) 3 1012 ph/s with E/E ~ 2 10-4 (15 keV)



Brief SIXS beam line description

• Solid surfaces and interfaces structures

• Nanostructures

• Self-organised surfaces

• Original in-situ growth

• Surface magnetic X-ray diffraction

• Surface in catalytic environment

• Solid-liquid electrochemical interfaces

• Buried soft interface

• Liquid-liquid interfaces

U20diaphragmDCMSi111

M1(V foc)

UHV M2 (plan)

MEDM3(H foc)

M3 (H foc)

Phase plate device

Surface and Interface XSurface and Interface X--ray Scattering (SixS)ray Scattering (SixS)A. Coati, B. A. Coati, B. VoisinVoisin, M. , M. SauvageSauvage, Y. Garreau , Y. Garreau

GIXD, GISAXS, XRR, magnetic X-ray scattering, coherent scattering

UHV UHV facilityfacility Multi Multi EnvironmentEnvironment facilityfacility

RingOHEH1EH2

UHV Diffractometer

ME Diffractometer

BeamBeam characteristicscharacteristicsDimensions : ~ 50x120 m2 (FWHM)Divergence: ~ 600x60 rad2

Dimensions : ~ 60x60 m2 (FWHM)Divergence: ~ 600x120 rad2

Open to users

in 2010

ScientificScientific CaseCase

Flux Flux 4 1013 ph/s with E/E ~ 10-4 (6 keV) 3 1012 ph/s with E/E ~ 2 10-4 (15 keV)



First optics hutchFirst experimental

hutch

Second

experimental

hutch

I14-C SIXS beam line display in the hall



SIXS first optics hutch

• Shielding designed for gas-bremsstrahlung scattering radiations and hard Xrays synchrotron radiations (500mA, 2. 10-9mbar)– Side Wall : 15mm of lead

– Back Wall : 80mm of lead

– Roof : 10mm of lead

• Empty of any optics elements at the moment of the radiation safety test– FE vacuum valve

– Filters chamber to protect Be window from beam power

– Safety shutter at the end of the hutch




Filters chamber

Beryllium window

Copper scatterer



Filters chamber

Beryllium window

Copper scatterer

Safety shutter



Radiation tests course

1. Checking alignment SR

source and FE elements at

low current

2. Leakage search around the

hutch at low current (<50mA)

3. Scattering g-BS and SR

radiation at max current

(400mA, 5.5mm U20 gap)

4. Complete radiation survey of

the OH with portable

radiameters and TLD



Radiation measurements (1)

Cu scatterer successive positions

Gamma & neutron monitors - SW

Gamma & neutron monitors - Roof

P1P2P3




Cu scatterer successive positions

Gamma & neutron monitors - SW

Gamma & neutron monitors - Roof

P1P2P3




120 TLD

Hp(10) & Hp(0.07)



• Farmer type ion-chamber

• PTW Unidos electrometer

• Behind 13mm lead screen to protect from BM SR light

• U20 undulator jaws fully opened to avoid any SR beam

Direct gas-bremsstrahlung

measurements




measurements




measurementsDirect gas-bremsstrahlung dose rate (mGy/h) as a function of stored beam

current intensity (mA)

0

20

40

60

80

100

120

0 50 100 150 200 250 300 350 400 450 500

beam current (mA)

Dir

ect

g-B

S D

ose R

ate

(m

Gy/h

)

• Taking into account natural background

• And vacuum residual gas static pressure

• Good agreement with quadratic fit depending to stored current level



Beamlines* MC calculations• Shielding design done assuming a « standard » residual gas

composition (2. 10-9mbar at 500mA) with large FE aperture 2x2 mm2

– H2 80%

– CO 10%

– CO2 5%

– CH4 3%

– H20 2%

• Actual residual gas RGA SOLEIL in vacuum ID (U20 SIXS)– H2 42%

– CO 30,4%

– CO2 5,6%

– CH4 3%

– H20 9%

– CF4 10%

• Reduced actual FE aperture (0,6 x 1,8 mm2 @ 11.7m)

Leads to higher gas-bremsstrahlung

production rate because of the higher

Z of residual gas

* MC code developped by P. Berkvens, see Radsynch07 proceedings



Bremsstrahlung source term

gas-Bremsstrahlung spectrum calculated for

different vacuum caracteristics

1

10

100

1000

10000

100000

1 10 100 1000 10000

gBS photon energy (MeV)

standard ESRF RGA

SOLEIL invac RGA

SOLEIL, invac + FE

SOLEIL, mixt + FE



Measurements results at 300mA

Photon ambient dose behind 15mm Pb SW - 300mA 1.5 10-8mbar

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

-200 -100 0 100 200 300 400 500

position behind SW - x=0 position of the scatterer

µG

y/h

February 17th

Pv(U20)=1.5 10-8 mbar

Portable ion

chamber

Fixed ion

chambers

(SW+door)

MC calculations



Measurements results at 400mA

Photon ambien dose rate behind 15mm Pb SW - 400mA P=1.5 10-8mbar

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0,5

-210 -110 -10 90 190 290 390 490

position along SW - x=0 (scatterer position)

µG

y/h

March 31st

Pv=1.5 10-8mbar

MC calculations

Portable IC for P1

Portable IC for P2

SW+door IC for P1

SW+door IC for P2



Cumulative troubles !

• High Z residual composition

• Full beam losses because of instabilities

• Concentration of the losses in the C14

straight section

• Presence of an obstacle in the straight ?



Dose observed during beam losses (1)

Integrated dose steps at beam

losses – 15mm Pb SW, FE open

0.42 µGy at 300mA

0.34 µGy at 300mA

0.23 µGy at 300mA



Maximum dose observed at 300mA

beam losses

0.42 µGy1.5 µGy

2 µGy




roof

sw

door

0.18 µGy at 400mA

0.5 µGy at 400mA

0.85 µGy at 400mA

µG

y4

1

2

3

0.5

2.5

1.5

3.5Cu scatterer in P2

(March 31st)




• Fortunatly dose observed with radiation

monitors are more or less confirmed by the

TLD results (Hp(10)) in terms of magnitude

order

– 6 300mA beam losses during the whole test

duration

– SW total dose : 3 µSv, ~ 0.5 µSv/beam loss

– Door total dose : 8.6 µSv, ~ 1.4 µSv/beam loss

– Roof total dose : 20 µSv, ~ 3 µSv/beam loss



SIXS U20 liner damages



Conclusion

• SIXS beam line Optics hutch shielding have been validated @ 400mA in decay mode of operation

• U20 in vacuum out of the ring now, but beam losses still occure in cell 14 in case of RF beam trip

there is probably a physical obstacle just a little upstream of the ID position

• Next shutdown, a new U20 in vacuum vessel will be installed on the ring to replace the former one

• Investigations will be done in order to find the obstacle

• An other radiation safety test is foreseen during the next run in order to validate the shielding during top-up mode operation at 400mA.



Aknowledgements

• Paul Berkvens, ESRF safety group

• Corinne Mage, SOLEIL radiation safety

group

• Fabien Justine, SOLEIL radiation safety

group



THANK YOU FOR YOUR

ATTENTION


Documents

Commissioning of an in-vacuum undulator beam line optics ... · and direct gas-bremsstrahlung measurements. ... DCM diaphragm U20 Si111 M1 (V foc) UHV M2 (plan) ... –Back Wall :