1. UCN and SCRF/ISAC interface issues ● proposal for UCN (CFI, 2008) – 10 uA at 25% duty cycle (1 min on, 3 min off) – use BL4A (TISOL) ● duty cycle is incompatible with ISAC targets, but may be necessary for low background for UCN experiments ● strategy for UCN (after discussions with SCRF/accel) – accept beam on BL4A when ISAC 2 nd target station is off, or part-time during target development periods, or when e-linac in operation (This could be a substantial part of the BL4 time initially available.) – accept sole user status in low-intensity periods so that duty cycle can be achieved at source. ● space requirements in proton hall can be managed (diagram to be crafted by Davis, Masuda, et al, circulated to Koscielniak) ● LHe source would not be common to e-linac, but could be housed in same space.

2. Future Upgrades (5YP and beyond) ● other options for duty cycle – fast kicker + local beam dump in hall ● local shielding of dump required ● reorganization of proton hall more appropriate to be on same time scale as ISAC 2 nd target station – manipulation of internal cyclotron beams ● requires further study – carbon stripper with mechanical motion in/out to pulse beam ● difficult ● other options besides sharing BL4 with ISAC – two stripper foils on same extraction probe + septum ● difficult, more appropriate for BL1 – BL1, BL5 ● major reconstruction – (gamma,n) or photofission source of neutrons (Behr) ● requires further study

3. ● other options besides sharing BL4 with ISAC (cont'd) – locate UCN source in ISAC target hall extension

4. Outline of White Paper ● Physics – prioritized and realistic, as much as possible ● UCN Source – proposed intensity at TRIUMF – world context and relevance ● Required Infrastructure – floorspace, shielding – duty cycle – He liquefier ● Required funding – CFI and collaboration, and international

5. Some key statements for the white paper ● ISAC 2 nd target station would use same beam line (BL4) ● e-linac would use same experimental hall (Proton Hall) ● UCN will not conflict with either program ● Even given the implied limitations, a UCN source at TRIUMF would be a world-class facility ● A flagship experiment at this UCN source would impact knowledge of fundamental interactions of neutrons

6. Beam Test Plan? TBD with Gerardo ● Acquire beam time as sole user, or with other users where duty cycle acceptable. ● Tune beam to BL4A. ● Demonstrate pulsed beam to BL4A with 3He neutron detector nearby. ● Try some more exotic solutions for pulsing? – manipulation of beams internal to cyclotron