The Polarized Internal Target at ANKE: First Results

The Polarized Internal Target at ANKE:First Results

Kirill Grigoryev

Institut für Kernphysik, Forschungszentrum Jülich

PhD student from Petersburg Nuclear Physic Institute (PNPI),Gatchina, Russia

Kyoto

October 03, 2006

03.10.2006 Kirill Grigoryev @ SPIN2006 2

COSY COoler SYnchrotron

• internal experiments – with the circulating beam (ANKE, COSY-11, EDDA)

• external experiments – with the extracted beam (BIG KARL, TOF)

with momenta up to 3.7 GeV/c

ANKE at COSY

Targets• Solid strip• Cluster jet• Polarized gas cell ( polarized gas jet )

Magnets• D2 – spectrometer magnet• D1, D3 – beam bending magnets

Detector systems• Positive & Negative• Forward & Backward• Spectator Detectors

Spectrometer ANKE

p, p, d, d→ →


Polarized Internal Gas Target

Setup at the laboratory

Summer 2003 – Atomic Beam Source is ready for using in experiments

PIT main components:ABS

• H or D• H beam intensity (2 HFS)

7.6 . 1016 atoms/s• Beam size at the IP

σ = 2.85 ± 0.42 mm• Polarization for hydrogen

PZ = 0.89 ± 0.01

PZ =-0.96 ± 0.01

Lamb-Shift PolarimeterTarget chamber with Storage Cell

Setup at the COSY experimental hall

End of 2004 – Start of the PIT transportation to the COSY experimental hall

ABS with infrastructure at the COSY experimental hall

Summer 2005 – After commissioning source is ready for installation at COSY

Setup at ANKE at COSY

July 2005 – ABS is installed at the ANKE-experiment area at COSY

Work only

Work only

beginsbegins


Magnetic Stray Field from D2 Magnet

x

y

z

90150135

61530

302555

4026300

200550300

60100300

303355

calculated field strength (G)measured field strength (G)permissible field strength for the device

given by the producer (G)

x

y

z

90150135

61530

302555

4026300

200550300

60100300

303355

x

y

zx

y

z

90150135

61530

302555

4026300

200550300

60100300

303355

calculated field strength (G)measured field strength (G)permissible field strength for the device

given by the producer (G)

ABS with shielded components at ANKE


Test of the Medium-field RF-Transition Unit

0 . 0 E + 0 0

5 . 0 E - 0 8

1 . 0 E - 0 7

1 . 5 E - 0 7

2 . 0 E - 0 7

2 . 5 E - 0 7

3 . 0 E - 0 7

0 200 400 600 800 1000 1200 1400D2 current, A

Pre

ssur

e in

the

tar

get

cham

ber,

e-7

mba

r .

H beam OFF H beam ON, states 1 + 2 H beam ON, state 1 only

3.0

2.5

2.0

1.5

1.0

0.5

0.0

field strength in the D2 gap0 T 1.58 T

0 . 0 E + 0 0

5 . 0 E - 0 8

1 . 0 E - 0 7

1 . 5 E - 0 7

2 . 0 E - 0 7

2 . 5 E - 0 7

3 . 0 E - 0 7

0 200 400 600 800 1000 1200 1400D2 current, A

Pre

ssur

e in

the

tar

get

cham

ber,

e-7

mba

r .

H beam OFF H beam ON, states 1 + 2 H beam ON, state 1 only

3.0

2.5

2.0

1.5

1.0

0.5

0.0

field strength in the D2 gap0 T 1.58 T

No dependence of MFT on D2 field No dependence of MFT on D2 field Shielding ok Shielding ok


PIT at ANKE

Using of the ABS at ANKE

jet target with storage cell

An additional methods to improve COSY beam

Electron cooling Stacking at injection

Stochastic coolingBeam scraping


ABS-jet test with catcher

Without

ABS jet

With

ABS jet

Without catcher

4.0·10-9 3.0·10-7

With catcher

4.0·10-9 3.7·10-8

ABS beam catcher

~13cm~13cm

Measured pressures in the target chamber, mbarN

um

ber

of

even

ts

integral thickness ~ 1.5 . 1011 cm-2

ABS BeamABS Beam

COSY BeamCOSY Beam


Storage cell setup

COSYbeam

XY-table Frame with storage cell and aperture

Target chamber

Feeding tube: l = 120 mm, Ø = 10 mm

Extraction tube: l = 230 mm, Ø = 10 mm

Beam tube : l = 400 mm, 20x20 mm2

400mm400mm

COSYbeam

XY-table Frame with storage cell and aperture

Target chamber

Feeding tube: l = 120 mm, Ø = 10 mm

Extraction tube: l = 230 mm, Ø = 10 mm

Beam tube : l = 400 mm, 20x20 mm2

400mm400mm


Cooler Stacking with the Storage Cell

ΘANKE beamNumber of accelerated protons to 600 MeV

no cell empty cell ABS H–fed cell

0°electron cooling 1.4x1010 3.5x109

Stacking + electron cooling

2.6x1010 2.0x1010

9.2° 6.0x109 6.4x109

28 stacks with 2s electron cooling

acceleration to Tp=600 MeVafter 58s from cycle start

Stored particles in the ring = 6.4 · 109 protons

H target thickness = 2 · 1013 atoms/cm2

Average luminosity > 1029 cm-2s-1

&&


Stochastic cooling

Cooling off

Cooling on

Tp=831 MeV

• Length of the cycle = 10 min • Minimum energy for stochastic cooling is 831MeV


PIT commissioning

N2 in cell

Tp=831 MeV

H2 in cell

Tp=831 MeV

Cell feeding with Nitrogenhelps to obtain background

from interactionswith the cell wall

Clear spot of the events from the cell-target gas

pp→dπ+ reaction


Target polarization from nuclear reaction

Used HFS 1 and 2 (only MFT).WFT would provide higher polarization in state 3, but did not work.

Tp=831 MeV

Assuming both polarization P+ and P- were equal P = 0.44±0.03

Theoretically we expect P+=0.85 and P-=-0.27(-0.18) P = 0.56 (0.51)

– HFS1– HFS2


Future plans

ongoing – Teflon coating and new cell production

Autumn ’06 – studies of nuclear polarization of molecules from

recombined polarized H and D atoms

use of the ABS in the other project ( ISTC #1861 )

December ’06 – PIT reinstallation with Lamb-shift polarimeter at ANKE

January ’07 – First double polarized experiment: dp → (pp)n→→

see talk D. Chiladze


Do we have zero field crossings along the ABS axis?

-200

-100

0

100

200

300

400

500

0 20 40 60 80 100

Bx By Bz Btotal

B, G

l , cm

1. Determine the local Larmor precession frequency ωL

2. The angular velocity of the magnetic field ωB.

As long as the ratio R=ωL/ωB is large, the spin of the atom follows the field direction. no depolarizationno depolarization

due to zero crossingsdue to zero crossings

Magnetic field along ABS axis• ID2 = 563 A• ID1D3= 1294.84 A

Magnetic field scan with ANKE at 5.3º using a 3D Hallprobe (Gatchina):

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

1.0E+08

1.0E+09

1.0E+10

0 20 40 60 80 100

wl wb wl / wb l , cm

Documents

The Polarized Internal Target at ANKE: First Results