9 June 1995 To: Distribution: From: Stan Ecklund Subject: "IR +- 1m Engineering" Meeting Notes 9 June 1995 Roy and Fred showed a new DMZ drawing which is changed in the backward HER direction, accommodating longer hybrid electronics. A model is being made of the region from Q1 to Q1. They are still working on smaller cables. Martin show a design of the B1 support bracket which is smaller and moves outboard, making more room for cable transitions. The z location of the Be-SS weld was discussed; it may move outboard to avoid infringement on the Vertex chamber. This looks OK if inside vacuum synchrotron coating extends to 300 mr cone. Elliptical (or non-round) water tubes should be considered in the tight area under the gimbals support; this will keep the pressure drop lower. Dave Coupal gave a status report on background simulations from radiative Bhabba scattering. He is considering rings of W material between B1 and Q1, as well as a cylinder around Q1. Also modeled are partial-azimuth sections inside of Q1 and outside of Q1 to accommodate the offset of Q1. So far he has results for the above shielding and air instead of W. Hits show up from the space between B1 and Q1. Next he will turn on/off various pieces of shielding to determine which are necessary. The no shielding rates are about 4 hits per crossing which is still less than the lost particle rate. He is also working on the MAD -> Turtle deck translation for the LER. Mike and Stan reported on Q1 geometries for a hybrid dipole- quadrupole design. This allows centering of the magnet in the support tube and smaller radii. A dipole field of 0.21 Tesla moves the Quad center 20 mm as previously obtained by offsetting the magnet. We donŐt know why this will not work, but it needs further study. Some worries are: harmonics, maximum field on block material, and forces. Beam stay clear issues were discussed briefly. Q1, Q2, Q4 and Q5 is OK with nominal betas and emittances, but in the interest of machine flexibility, apertures may be close and limited by same. It is important for synchrotron radiation that there be no particles out past 10 sigma in the near IR. Action Items: 1. Consider hybrid Q1 feasibility. [Martin, Stan, Mike,..] 2. Look for ways to reduce cable interference. [Roy] How much z space at Q1 inboard end is needed? 3. Temperature Specifications for B1, Q1. [Hobey] 5. Drawing Updates: [Martin Nordby, Fred Goozen] Shielding, rotated BPM, Radial Ion pump,... 6. HOM RF calculations with new mask geometry. [Eddie Lin] 7. Check that a rotated BPM misses synchrotron rad fan. [Mike] 8. Maintain list of support tube parameters. [Hobey] add Q1 radii, offset, support barrel radii,... 9. Can we do with less shielding between B1 and Q1? [D. Coupal] 10. Required thickness of Q1 containment. [Martin] 11. Required thickness of Support Tube. [Martin] 12. Mask cooling calculation. [J. Hodgson] Next Meeting: 13:00 Friday 16 June 1995 in the Yellow room with TV to LBL attachments: transparencies