a polarized solid state target for photon induced double polarization experiments at elsa h. dutz...

A polarized solid state target for

photon induced double polarization experiments at

ELSA

H. DutzTR16 Bommerholz 06

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Hartmut Dutz, S. Goertz, A. Raccanelli,A. Wagner, F. Zarife

Status of the project‚Polarisierte Festkörpertargets‘

D.1 Bonn


photon induced double polarization experiments

at ELSA

Status ofD.1 Bonn

IntroductionStatus

Set-up @ ELSANew CryostatInternal Magnet

Conclusion

> IntroductionStatus


Conclusion

Status of the project‚Polarisierte Festkörpertargets‘

D.1 Bonn


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at ELSA

Status ofD.1 Bonn

TR16 request 11/2003

D.1.3.5 Work Program (Goals, Methods, Timetable)

•‚GDH – Frozen Spin Target‘ at Crystal Barrel•‚4 – continuous mode‘ polarized solid state target•development of an internal superconducting solenoid



Conclusion


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Horizontal frozen spin target‚GDH – Frozen Spin Target‘

21

23

0

d

I GDHp

Bonn/Mainz 1998-2003



at ELSA

Status ofD.1 Bonn

Specially designed for the GDH experiment @ MAMI and ELSA



Conclusion


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Circular / linear polarized tagged photons (107 /s)

Longitudinal polarized nucleons

NN

NN

fPPGE

tbz

1~,

CB-ELSA 2006 …


5 proposals using polarized protons (ELSA-1,2,4,6,7)1 proposal using polarized deuterons (ELSA-3)



at ELSA

Status ofD.1 Bonn



Conclusion


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-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17-10

0

10

20

30

40

50

60

70

80

90

t = 143 min

Mainz '98 Bonn '01

t = 43 min

t = 177 minpo

lariz

atio

n [%

]

time [hours]

PMZ= 87.7 %1.3%PBN= 83.4 %1.1%


Max. proton polarization @ 2.5 Tesla (butanol)



at ELSA

Status ofD.1 Bonn

0 50 100 150 200 250 300 350 4000

10

20

30

40

50

60

70

80

90

100

D-butanol (trityl-complex) D-butanol (porphyrexide)

6LiDd

-po

lari

zati

on

[%

]

Time [h]



Conclusion


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Pmax ~ 72 %




at ELSA

Status ofD.1 Bonn

Max. deuteron polarization @ 2.5 Tesla (butanol/6LiD)

Pmax ~ 30 %

0.2 0.3 0.4 0.5 0.6 0.7 0.810

100

1000

p-butanol T~63mK p-butanol 65<T<110 mK

(Mainz/Bonn '98-'01) p-butanol T~85mK (Bonn '02)

6LiD T~85mK (Bonn '02) d-butanol T<85 mK (Mainz '03)

Re

lax

ati

on

tim

e [

ho

urs

]

'holding field' [Tesla]



Conclusion


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at ELSA

Status ofD.1 Bonn


t(p-but/d-but) 200 h @ 85 mkt(6LiD) 4500 h @ 85 mk

Relaxation – times of various target materials

Introduction>Status

> Set-up @ ELSANew CryostatInternal Magnet

Conclusion


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at ELSA

Status ofD.1 Bonn

‚CB – Frozen Spin Target‘Set-up @ ELSA


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at ELSA

Status ofD.1 Bonn

Introduction>Status


Conclusion



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at ELSA

Status ofD.1 Bonn

‚CB – Frozen Spin Target‘Status Set-up @ ELSA

Introduction>Status


Conclusion

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40100

1000

10000

100000

R

(O

hm)

Time (h)

AB Still AB Spule AB Cavity

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40100

1000

10000

100000

R (

Ohm

)

Time (h)

AB Still AB Spule AB Cavity

Set-up completed first cool down to 1 K in Oktober

26/27-10-06 22/23-04-02

Thermal contact between internal .rad. shield and Still has been fixed

Next steps:

•cool down to 1K and into dilution mode•activating NMR and microwaves•polarizing Butanol and measure relaxation times


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at ELSA

Status ofD.1 Bonn

Introduction>Status

Set-up @ ELSA> New Cryostat

Internal MagnetConclusion

‚4 continuous mode target‘

Horizontal dilution refrigerator incl. internal polarizing magnet for CBRefrigerator in refrigerator system (4He eva. - 3He/4He dil.)

high cooling power @ 300 mKopt. run as ‚frozen spin target‘ Tmin ~ 50 mK

• good angular acceptance (~ 4)• high luminosity L ~ 1033/cm²s (N 1010/s)• high mean polarization• good beam time efficiency


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at ELSA

Status ofD.1 Bonn

Introduction>Status




Outer vacuum jacket


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at ELSA

Status ofD.1 Bonn

Introduction>Status




Turbine like precooling stages


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at ELSA

Status ofD.1 Bonn

Introduction>Status




Turbine like heat exchangers for the pre cooling stage


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at ELSA

Status ofD.1 Bonn

Introduction>Status




Smooth transitions for HTSC – current leadsevaporator – still shielding

Self cooled Insert – sealing


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at ELSA

Status ofD.1 Bonn

Introduction>Status




Still cone for smooth HTSC bending


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at ELSA

Status ofD.1 Bonn

Introduction>Status




Internal superconducting polarizing magnetdisc. final sintered heat exchanger


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at ELSA

Status ofD.1 Bonn

Introduction>Status

Set-up @ ELSANew Cryostat

> Internal MagnetConclusion

‚internal superconducting polarizing magnet‘

Requirements:

High field (~2.5 T) +

High homogeneity (ΔB/B ~10-4) in the target region

Constraints on:

- Magnet thickness (particle absorption)- Number of Bias Leads (heat load)

- Mechanical feasibility

SC winding

Targetregion

Any FEM – model on the market:

Requires a try and error (manual) approach and has a poor flexibility

old Feld.c – code failed

Hom. volume ~ mag. volume


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at ELSA

Status ofD.1 Bonn

Introduction>Status




A. Raccanelli, F. Zarife, in collaboration with R. Krause, IAM-Bonn

Allows one to study the effect on the field homogeneity of:

- Limited accuracy in the winding - Irregularities (random variations in the coil number in a layer)- SC wire diameter

Allows the implementation of optimization algorithms

A new code performing integration on the actual coils

Calculations need to be tested / proofed


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at ELSA

Status ofD.1 Bonn

Introduction>Status



‚internal superconducting polarizing magnet‘Status

High field holding coil:1.8 T @ 4.2 K

Field mapping system, flux gate magnetometer


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at ELSA

Status ofD.1 Bonn


Introduction>Status



Next Steps:

JLAB transverse coil (failed 2006):

Horizontal polarizing coils: simulate, wind and test NC coilstransverse holding coil : saddle coils, racetrack type, field ~ 0.5 T

only in ‘frozen spin mode’


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at ELSA

Status ofD.1 Bonn

IntroductionStatus


> Conclusion

Conclusions / Outlook

‚CB – frozen spin target‘ has been proofed as a reliable tool to study double polarization experiments @ ELSA

ready for operation and data taking

4 – continuous mode‘ target:

Transverse field magnet project needs further serious investigationand dipl. – PhD - students

‘high luminosity, large acceptance’ polarized solid state targetinternal polarizing magnetno railway system required

longitudinal polarization directiontransverse polarization as a frozen spin target

electron scattering experiments in a 4 detection systemmechanically completed 2008/2009



Conclusion


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Horizontal frozen spin target‚CB – Frozen Spin Target‘



at ELSA

Status ofD.1 Bonn


- 24 -



at ELSA

Status ofD.1 Bonn

Introduction>Status


Conclusion



- 25 -



at ELSA

Status ofD.1 Bonn

Introduction>Status


Conclusion



- 26 -



at ELSA

Status ofD.1 Bonn

Introduction>Status


Conclusion



- 27 -



at ELSA

Status ofD.1 Bonn

‚4 continuous mode target‘Status

Introduction>Status



Next Steps:

Design of the horizontal dilution refrigerator nearly completedOuter vacuum jacket is finished and vacuum testedThin wall stainless steel tubing delivered or machinedTurbine heat exchangers machinedInner cone machined and soldered

Design of the final heat exchanger has to be completedPre cooling stages (separator, evaporator) Dilution unit incl. design of the mixing chamber Assembling of the complete refrigeratorInternal superconducting polarizing magnetAim: mechanically completed 2008/2009

a polarized solid state target for photon induced double polarization experiments at elsa h. dutz...

Documents

elsa status of

elsa slide

polarized solid state

polarized deuterons

polarized protons elsa

solid state target development

dutz tr16 bommerholz

zarife status