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Electric Field for the dEDM Experiment at the BNL AGS

Vasily DzhordzhadzeSPIN 2008, Charlotesvelle

October 10, 2008

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dEDM Experiment at BNL AGS

• Presented at the SPIN 2008 Conference by Y.Semetzidis, G.Onderwater, M. Silva, F.Lin

• Goal: Measurement of the deuteron electric dipole moment at 10-29 e.cm level

• Principle: Polarize; • Interact with a E-Field; • Analyze Spin as a function of time

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Clock Wise (CW) and Counter Clock Wise (CCW) injections

• CW and CCW injections to cancel all T-reversal preserving effects as, e.g., the out of plane <E-field>. EDM is T-violating and behaves differently.

• Issue: Stability as a function of time• Solution: Use the 2-in-1 magnet design for

simultaneous CW and CCW storage (Morse) or Gupta’s common coil magnet.

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E-field Plates Specs• E-field: 120KV/cm with 2cm plate separation. The

design should restrict E-field<=120KV/cm everywhere• Two beams stored at the same time. They should not

influence each other electrically: min distance between the two beams is >15 cm.

• E-field uniformity: quad component < 1ppm distance from end > 10cm; align plates to 1um.

• E-field stability requires temperature stability

dT<10-3K; strong, sturdy plates• Need to operate in a magnetic field: study and

eliminate trapping effects

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E-field Plates• 2 cm apart

• Plate thickness: ~1.5cm, Stainless steel

• Height: 40-60cm, may be taller

• Length ~3.3m/ea, 32 plates (16 pairs) total around the ring

• Radius of curvature: ~8.5m

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E-field plates: ~60cm high

• Aim for 10-5K/m temperature uniformity

Vacuum chamber

Stainless steel support

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POISSON Simulation of E-Fields

2 cm separation , r=2 cm 2 cm separation , r=5 cm

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Common Coil Design for EDM

Aperture #1

Aperture #2

Coils

Coils

Iron Yoke

From R. Gupta’s presentation

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E-field strength

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E-field strength

The field emission with and without high pressure water rinsing (HPR).

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• Electro polishing (EP)• Buffered Chemical Polishing -> Surface

treatment by chemical solutions of NHO3, HF, H3PO4 (1: 1: 2): removal of 150 m for 90 minutes or 30 m for 20 minutes

• Surface roughness measurements by profilometer (2m)

• High Pressure Water Rinsing

Metal finishing

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ELECTROPOLISHING

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Before EPBefore EPBefore EP

After EP

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High Pressure Water Rinsing

Consist of High pressure pump, a spray wand and custom Nozzles. Systems are used as the final step in the surface Preparation. Uses ultra pure water with a pressure of ~1000psi to remove all remnants of the mechanical finishing. Output pressure can reach 3000 psi. Water supply ~500 gallons. Rinsing process is fully programmable by a PC running LabView.

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High Pressure Water Rinsing

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E-field strength, Electrostatic Separators at Tevatron

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E-field strength, Electrostatic Separators at Tevatron

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E-field strength, Electrostatic Separators at Tevatron

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E-field strength, Electrostatic Separators at Tevatron

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• FNAL 170 KV/late: no sparks in 7 days• Scaled to 2cm: gives 107 KV/cm, conditioned at

114 KV/cm. Scaled to 1.4cm : 128 KV/cm conditioned at 136KV/cm

• Using HPWR we expect to achieve the 120 KV/cm strength at 2cm and certainly at 1.4 cm

• O. Prokofiev (FNAL): It will require work but it can be done

E-field strength choice: 12 MV/m

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Measuring gravity direction with inclinometer of 10-10 rad sensitivity

Caution:Moon’s max gravitationaleffect is ±3.5rad!Distance: 60 times earth’s radius and mass ~1% ofearth’sWe need to take it into account when using the inclinometer!

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• We launched two programs for using BNL facilities for testing of the E-Field and gravitational stability

• We will use a clean room available at a new Center for Functional Nanomaterials to assembly the vacuum chamber with plates and test them later.

• We will get vibration free and strict temperature controlled room for our gravitational and position tests using inclinometer

• Later tests will start immediately• Vacuum Chamber tests will start January 2009• Expected first experimental results by Aril 2009

Summary