Issues

1. Issues A0 beam is 16 MeV. NML beam will be up to 50 MeV. Are the present set of A0 magnets adequate for the higher beam energy at NML? Limitations could be temperature, or fringe field, or .... We (Jamie and I) measured the magnet temperature of the A0 quads (blue and green) and chicane dipoles at higher currents. I made a survey of the accumulated data on these magnets. A0 Magnet Issues for NML – M Church 12/5/07

2. Chicane Dipoles  ~9.5A is probably about the maximum current we can safely run these magnets. Magnetic field measurements by TD @ 4.5A give a bend angle of 15.8° @ 50 MeV for trapezoidal pole piece. Assuming no iron saturation, we will require 6.4A to bend 50 MeV beam by 22.5°. However, there is some (anecdotal) evidence that these magnets start saturating above ~4A. (25% @ 6.5A according to G. Gollin grad student!) I recommend: 1) Send a single spare magnet (with both types of pole pieces) to TD for field and temperature measurements at 4.5A, 6.5A and 9.5A. Field measurements should consist of measurement of By vs x and z on the y=0 plane. We will need this information anyway for accurate particle tracking. 2) Decide on the basis of these measurements if the magnets (or the beamline design) require modification for NML. TD measurement of By vs I A0 Magnet Issues for NML – M Church 12/5/07

3. A0 Quads 1st measurements were done at 9.8A (blue quad) and 6.7A (green quad). Both magnets got over 195 degF in 55 min and temperature was still increasing. If we assume the coil temperatures at left are at the maximum safe current, the gradients are limited to ~3.7 T/m (blue quads) and ~4.2 T/m (green quads). Information in hand is a bit confusing. Radiabeam data sheet indicates peak gradient of 4.1 T/m for the EMQ-0200-01. Old lattice files state a maximum gradient of 6-7 T/m. We are waiting for a definitive answer from Radiabeam. .... I recommend: 1) Get a definitive answer from Radiabeam on the safe current limits of these quads, and also the new EMQ-0200-02. 2) Repeat lattice calculations with the new constraints (Philippe). In the latest lattice design not all quads adhere to the above constraints on gradient. 3) A measurement of gradient vs. z exists for a blue quad. I would like to see this measurement done for a green quad. Will have to wait until we move to NML? A0 Magnet Issues for NML – M Church 12/5/07

4. NDA (spectrometer magnets) The (pole-tip modified) NDA magnets at A0 can be used for the bends in the NML LE test line and the LE dump. Some years ago, at the request of the Pbar Source, TD established a safe upper limit for NDA magnets of ~25A. (The data is accessible on the web.) Kip Bishofberger measured the field at up to ~10A. Scaling from this data, a bend of 22.5° at 50 MeV will require a current of ~15.5A. The maximum current of 25A corresponds to a bend of ~36° at 50 MeV. I recommend: 1) We ask TD to measure the field of one of these magnets at 15.5A and 25A. The field measurements should consist of By vs. x and z for the y=0 plane. Can we do this before A0 is completely decommissioned? 2) The LE dump line for NML should be redesigned for ~36° based on the field measurements at 25A. A0 Magnet Issues for NML – M Church 12/5/07