polarized h - and d - beams at cosy/j ü lich

Institute for Nuclear Physics (IKP) [email protected]

Ralf Gebel – PSTP 2007 – 10.-14.September 2007

• Facility overview • Ion sources at COSY• R&D details

• Cs ionizer• Extraction • Actual investigations (ABS, LSP)

• Summary and outlook

Polarized H- and D- Beams at COSY/Jülich



The COSY Facility• 0.6 .. 3.65 GeV/c p and d

• polarized beams

• beam cooling

• internal and external detectors for the investigation of nuclear quark structure and dynamics, fundamental symmetries and e.g. exotic mesons, rare decays

COoler SYnchrotron



The COSY Injector



Light Ions for COSY



0000 CsHCsHHILnI

vA

LII

Charge exchange reaction

H0(D0) + Cs0 H-(D-) + Cs+

The COSY Polarized Source

RF dischargeThermal ionizer

38 K1150 K550 K



The COSY Polarized Source



Atomic Beam Source

Cesium Ionizer

and

Beam Line

The COSY Polarized Source (II)



Cs Ionizer – Replacement of the Prototype

S. Lemaitre’s and R. Reckenfelderbäumer’s Ph.D. thesesNIM A 408, 345 (1998)



Tungsten Ionizer



Next Iterations

M. Eggert’s Ph.D. thesisNIM A 454, 514 (2000)



Pulsed Version



• dc and pulsed operation (0.5- 3 Hz)

• 6 mA routinely @ 45keV – 25 ms 0.5 Hz

• up to 1500 hours continuous operation for COSY and experiments

• 3 sources for exchange

Development of Cs+ Sources

-4 kV

-5 kV

-6 kV

-7 kV

-7.5 kV

0

4

8

12

mA

Emitted Cs+

current

Emitted Cs+ current

5.5 mA

20 ms

55°C

60°C

65°C



A set of computer controlled wire scanners

• for Cs+/o diagnosis

• to judge the beam and the ionizer quality

• to optimize Cs+/o transmission

• space charge compensation by adding Argon

Focusing the Cesium Beam



Field Gradient inside the Solenoid

1994

2005



Beam Current vs. U and B



Extraction and Deflection



Improvement of Beam Extraction

H- Cs+, Cs0Mounting the extraction elements



Focusing the Atomic (H, D) Beam

Monte-Carlo simulation

Integration over r, r’, spin and velocity

-20

0

20

Rad

ius

[mm

]

0.0 0.4 0.8 1.2 1.6Distance to 2nd hexapole [m]

0

5

10

15

20

25

Rad

ius

[mm

]

0.0 0.5 1.0 1.5Distance to 2nd hexapole [m]

60 %70 %80 %

90 %Solenoid



Exchange of the EM hexapoles

EM diameter 220 mm

PM diameter 80 mm

220

mm

M. Altmeier’s and O. Felden’s Ph.D. thesesNIM A 626, 117 (1997)



Neutral Beam Profile Scanner

Estimation of the atomic beam size and position by using the Cs scanner inside the atomic beam part and a compression tube

0,E+00

2,E+15

4,E+15

6,E+15

8,E+15

1,E+16

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

horizontal wire position [ mm ]

inte

ns

ity

[a

tom

s /

se

c ]

0,E+00

1,E+16

2,E+16

3,E+16

4,E+16

5,E+16

6,E+16

inte

gra

ted

sig

na

l

0,E+00

2,E+15

4,E+15

6,E+15

8,E+15

1,E+16

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

vertical wire position [ mm ]

inte

ns

ity

[ a

tom

s/

se

c ]

0,E+00

1,E+16

2,E+16

3,E+16

4,E+16

5,E+16

6,E+16

inte

gra

ted

sig

na

l



2 4 6 8 10 12 14 160

20

40

60

80

100

120

140

160

180

200

ato

mic

hyd

rog

en

be

am

de

nsi

ty(T

OF

- m

V)

number of molecules (rel. units)

T_n = 36 K T_n = 77 K

2 4 6 8 10 12 14 16

600

800

1000

1200

1400

1600

1800

2000

2200

2400

mo

st p

rob

ab

le v

elo

city

(m

/s)


T_n = 36 K T_n = 77 K

2 4 6 8 10 12 14 160

20

40

60

80

100

figu

re o

f me

rit


T_n = 36 K T_n = 77 K

Estimation of density and velocity

The density was measured with a TOF mass spectrometer.

Figure of merit = density / v²

(magnet acceptance ~ 1/T)



Dissociator Development



Improved Density with new Design



Lambshift Polarimeter



Lambshift Polarimeter

Ready for first beam!



Summary: Intensity record for deuterons

unpolarized deuterons switching to polarized deuterons



Summary: Intensity and polarization

Beam current at the source exit Polarization inside COSY

Data from Exp. EDDA

(pp – elastic scattering)

Pavg = (91.4 2.2 ) %



Outlook

• Beam for the Lambshift Polarimeter

• Improved atomic beam stage for COSY Operation

Thank you! Thank you!

Acknowledgments: A.S. Belov (ABS, LSP...)R. Engels (LSP)

polarized h - and d - beams at cosy/j ü lich

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