Minutes SHMS MC 6

Minutes of SHMS MC working group meeting 11/02/2011

Participants: Dave, Dipangkar, John, Howard, Mark and Peter

1. The optics studies so far suggest that the 26 cm offset between the dipole central axis and the spectrometer horizontal axis is the best for the acceptance. The COSY and SNAKE comparisons show that they are consistent with each other. Howard and Mark are and will continue to coordinate with Mike Fowler, Steve Lassiter and Paul Brindza on this and make sure that this gets passed on to the designers and gets implemented.

2. The events lost in the dipole were also investigated with the new offsets. The reasons for the concentration of the loss of events at +x (ie bottom of the dipole aperture) was discussed. It was concluded that it is preferable to have the loss of events at the front of the dipole rather than at the back of the dipole to minimize the possibility of rescattered events making it into the focal plane. This (losses shifted towards the front) is indeed the case for the larger 26 cm offset compared to the 20cm offset

3. Various options for collimators were discussed. There was agreement that it is probably better to have a large and a small collimator. Details of their preferred dimensions will be worked out at the next meeting. This is because all the COSY plots that were being used in the dicussion were for D/M = 0.08 instead of the nominal 0.12. Once the plots are regenerated for D/M=0.12 we will continue to discuss the dimensions of the collimator. We also need to verify that 3 collimators (2 octagons and 1 sieve slit) will fit in front of the Q1.

4. Peter noticed that the beam envelopes at the Drift chambers were narrower along y compared to previous simulations. This could be of concern, but these plots also need to be generated for D/M=0.12