1. Takeyasu Ito University of Tennessee EDM Collaboration meeting August 19-20, 2004 Nature of a Separate Production Cell What dimensions are appropriate and what UCN density can be achieved? What fill time for the production cell (4 liter) will be required with a 1” aperture connecting pipe? What should be the time for the ultra- pure helium to become contaminated with 3 He?

2. Takeyasu Ito2 Model Measurement cell Production cell Connecting tube Beam Parameters Measurement cell volume: V m = 7cm x 10cm x 50cm = 3500cm 3 Connecting tube cross sectional area: A tube =  (2.5/2) 2 = 5cm 2 Production volume length: L p =100 cm Production volume cross sectional area: A p =20cm x 20cm = 400 cm 2 Beam cross sectional area: A beam = 10cm x 10cm = 100 cm 2 UCN production rate: R p = 1 ucn/cm 3 /sec UCN velocity: v ucn = 600 cm/sec Cell lifetime:  cell = 1200 sec Neutron lifetime:  beta = 886 sec

3. Takeyasu Ito3 Equations When the valve is closed: When the valve is open:

4. Takeyasu Ito4 Results UCN density nmnm npnp Valve opens at t=2500 s Time (s)

5. Takeyasu Ito5 Results UCN density nmnm npnp Valve opens at t=2500 s Time (s)

6. Takeyasu Ito6 Summary UCN density in production cell Production cell fill time UCN density in measurement cell Measurement cell fill time In order for n m sep ~n m combined, V p »V m If  p cell >  m cell, then perhaps n m sep > n m combined possible