The Polarized Internal Gas Target of ANKE at COSY

The Polarized Internal Gas TargetThe Polarized Internal Gas Targetof ANKE at COSYof ANKE at COSY

PST 05PST 05

Tokyo, JapanTokyo, Japan

November 16,November 16, 200 20055

Ralf EngelsRalf Engels

Institute for Nuclear Physics (IKP) Institute for Nuclear Physics (IKP)

Forschungszentrum JülichForschungszentrum Jülich

16.11.200516.11.2005 Ralf Engels @ PST 05Ralf Engels @ PST 05 22

COSY COSY COoler SYnchrotron COoler SYnchrotron

COSY:

• storage ring for (un-) polarized proton and deuteron beams• with momentum up to 3700 MeV/c

COSY used for:

• internal experiments - with the circulating beam (ANKE, COSY-11, EDDA, PISA)• external experiments - with the extracted beam (BIG KARL, JESSICA, NESSI, TOF)


PIT setupPIT setup

Setup at the laboratory

Polarized internal gas target setup at the laboratory consist of:

• Atomic Beam Source

• Test chamber with storage cell prototype

• Lamb-Shift Polarimeter


Atomic Beam SourceAtomic Beam Source

PI I ~ 10 mbar-6

PI ~ 10 mbar-4

PI II ~ 10 mbar-7

PIV ~ 10 mbar-8

1st group of 6-pole magnetsPole-tip fields are:

#1 1.654 T 10/14 mm

#2 1.684 T

#3 1.625 T

16/22 mm

mm28

2nd group of 6-pole magnetsPole-tip fields are:

#4 1.565 T

#5 1.621 T

#6 1.621 T

30 mm

30 mm

30 mm

Nozzle cooling systemTemperature range: 50-300 K

DissociatorPrimary flow (H /D ) range: 1 10 - 5 mbar l/s

Second2 2 -3

ary flow (O ) range: 1 10 - 0.5 mbar l/sRF power: 0 - 600 W @ 13.56 MHz

2 -3

Medium Field Transition unit (MFT)Frequency: 58.7 MHz (H )Magnetic field: up to ~ 2 kG

2

Strong Field Transition unit (SFT)Frequency: 1425.2 MHz (H )Magnetic field: up to ~ 3 kG

2

Weak Field Transition unit (WFT)Frequency: 14 MHz (H )Magnetic field: up to ~ 3 kG

2

Movable bafflesAl casting

Central reference platestainless steel (t ~ 50 mm)

H beam intensity~ 8.0x1016 at/s


ABS beam profileABS beam profile

σ = 2.85 ± 0.42 mm


Ionizer

Wien filter Cs cell Spin filterQuenchingchamber

Ph

otom

ultip

lier

tB

B

B

Cup

ABS

Deflector

B B

Lamb-Shift Polarimeter layoutLamb-Shift Polarimeter layout


ABS beam polarization measurementsABS beam polarization measurements

Ly-α spectra of hydrogen and deuterium measured with LSP

Hydrogen

P = 0.89 0.005z ±

P = –0.96z ± 0.005

300 350 400 450 500 550

Magnetic field, a.u.

P

P

z

z

(Ly-a) = +0.78MFT 2-3

teor= +1

mI=–1/2

50 100 150 200 250 300 350 400 450 500 5500

20

40

60

80

100

120

140

160

180

N(L

y-a)

P

P

z(Ly-a) = -0.86MFT 2-3WFT 1-3

zteor

= -1

mI=+1/2

mI=–1/2

Deuterium

P = 0.73z P = –0.82z

500 550 600 650 700 750 800 850

40

60

80

100

120

140

160 P

P

z(Ly- ) = +0.68

MFT 3-4SFT 2-6

aP

P

zz

z

(Ly- ) = +0.68

= +1= +1

a

z

z

teor

teor

N(L

y-)

a

mI=+1

mI=–1mI=0

500 550 600 650

40

60

80

100

120

140 P

P

z(Ly- ) = -0.76

MFT 3-4WFT 1-4 2-3

aP

P

zz

z

(Ly- ) = +0.57

= -1= +1

a

z

z

teor

teor

N(L

y-)

a

mI=+1 mI=0

P = 0.77zz P = –1.17zz

500 550 600 650 700 750 800 850

40

60

80

100

120P

P

z(Ly- ) = 0

WFT 1-4SFT 2-6

aP

P

zz

z

(Ly- ) = +0.72

= 0= +1

a

z

z

teor

teor

N(L

y-)

a

mI=+1 mI=–1

mI=0

500 550 600 650

40

60

80

100

120

140

N(L

y-)

a

mI=+1

mI=0

Magnetic field, a.u.

Magnetic field, a.u. Magnetic field, a.u.

Magnetic field, a.u. Magnetic field, a.u.

150 200 2500

20

40

60

80

100

120

140

160

180

N(L

y-a)

mI=+1/2

700 750 800 850

mI=–1

700 750 800 850

P

P

z(Ly- ) = -0.06

WFT 1-4SFT 3-5

aP

P

zz

z

(Ly- ) = -1.09

= 0= -2

a

z

z

teor

teor

mI=–1


Ato

mic

Be

am

Sou

rce

Storagecell prototype

Ionizer Wien filter Cs cell Spin filterQuenchingchamber

Pho

tom

ultip

lier

tB

BB B B

Cup

How to measure polarization in the cellHow to measure polarization in the cell

Layout of the test setup at laboratory

ABSbeam

COSYbeam

Target gassample


LSP resultsLSP results


LSP resultsLSP results


How to measure polarizationHow to measure polarization


PIT at COSY hallPIT at COSY hall


PIT transportationPIT transportation


PIT @ ANKEPIT @ ANKE


PIT @ ANKEPIT @ ANKE

Technical constraints• Installation time of the PIT is limited to 3-4 days

• D2 is movable →→ needs sophisticated supporting bridge between D1 and D2

• Tunnel width is limited →→ 60° angle between LSP components

• ABS axis is 50 cm away from D2 yoke →→ shielding from the stray field is needed Polarized internal gas target setup at ANKE

Storage cellPolarimeter

ABS


Stray field measurementsStray field measurements

x

y

z

90 G150 G135 G

6 G15 G30 G

30 G25 G55 G

40 G26 G300 G

200 G550 G300 G

60 G100 G300 G

30 G33 G55 G

30 G - maximum calculated field magnitude45 G - measured field magnitude55 G - allowed field for device

30 G17 G

150 G48 G

30 G - measured field without shielding 17 G - measured field with shielding

x

y

z


0.00E+00

5.00E-08

1.00E-07

1.50E-07

2.00E-07

2.50E-07

3.00E-07

0 200 400 600 800 1000 1200 1400

Current in D2, A

Pre

ssu

re in

th

e ta

rget

ch

amb

er, m

bar

.

beam off beam on, no polarization beam on, with polarization

1.00E-08

Polarization test with D2 fieldPolarization test with D2 field

Pz ~ 0.80


Apertures tests at COSYApertures tests at COSY

COSYbeam

XY-table Frame with apertures

Vacuum chamber


Principle of the apertures tests at COSYPrinciple of the apertures tests at COSY 1. Beam in the center of the aperture

50 mm

2. Aperture moves to the right until intensity drops +5 mm

3. Aperture moves to theleft until intensity drops 11 mm

Distance 3

Distance 2

Beam diameter = Aperture inner width - ( Distance 2 + Distance 3 )

Beam intensity is maximum

0

100

200

300

400

500

600

700

800

-25 -20 -15 -10 -5 0 5 10 15 20 25

X coordinates, mm

bea

m in

ten

sity

, a.u

.

Beam intensity starts to decrease

0

100

200

300

400

500

600

700

800

-25 -20 -15 -10 -5 0 5 10 15 20 25

X coordinates, mm

bea

m i

nte

nsi

ty,

a.u

.

Distance 2

Beam intensity starts to decrease

0

100

200

300

400

500

600

700

800

-25 -20 -15 -10 -5 0 5 10 15 20 25

X coordinates, mm

bea

m i

nte

nsi

ty,

a.u

.


Estimated COSY-beam profileEstimated COSY-beam profile

at injection with an accelerated beam

no target with cluster target(density ~ 1014 at/cm2)

36x16 mm 9x12 mm 16x15 mm


Cell test preparationCell test preparation

Aperture → 40 x 25 mm

Big cell → 30 x 20 x 220 mm entrance 600 mm2

Small cell → 15 x 15 x 220 mm entrance 225 mm2


PRELIMIN

ARY

Results of the cell testResults of the cell test

Target densityfor the large cell

9.4 * 10132cm

at Ratio target/backgroundfor the large cell

~ 3 – 4

Injected deuteronslarge/small cell ~ 7 – 8 Estimated target density

H2 for the small cell ~3 * 1014

2cm

at

Tests were carried out with unpolarized hydrogen gas flux ~ 10-3 mbar l/s

No cooling of the ion beam !!!


SummarySummary

• PIT moved to COSY hall since December 2004

• PIT installed at ANKE in June-July 2005

• PIT is running since September 2005

• Cell tests without cooling in Spring 2005

Cell tests with electron cooling shifted to November 2005

• LSP will be used to measure direct beam of the ABS

• Polarization in the cells determined by the Spectator counters


OutlookOutlook

November ’05 – next cell tests with cooling and stacking of the COSY beam

November ’05 – commissioning of the ABS-jet target at COSY

Winter ’05-’06 – ANKE target exchange from PIT to Cluster target

May ’06 – one more week for cell test at COSY

Until June ‘06 – more tests with LSP in COSY hall

new cell production with teflon coating

ISTC project 1861 : “Measurement of the nuclear

polarization in H2 / D2 molecules”

Summer ’06 – PIT reinstallation at ANKE

Autumn ’06 – first data production with jet target at ANKE

(http://www.fz-juelich.de/ikp/anke/en/proposals.shtml)

Polarized fusion


ISTC project 1861ISTC project 1861


Polarized fusionPolarized fusion

LSP

Electrostatic lenses

IonizerInsulator

2D silicon strip detectors “Interaction box”

potential 1kV-200kV

“Hot” magnets for holding field

LSP under thepotential respectto the “ground” 500V

Cryopump

90 electrostatic deflectors

o

Wienfilter

ABS

The Polarized Internal Gas Target of ANKE at COSY

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