Notes from Main Injector/Recycler Group Meeting Monday 4 November 2002 Bruce C. Brown Shekhar Mishra -- RR Operation at MI Momentum Using the prescription worked out by Bill Foster, the momentum of the Recycler has been raised to the Main Injector injection momentum. The dipole correctors are being used to provide the required extra bending. The change in momentun is 24 MeV/c using ~ 1.3 A in the dipoles with a peak change of 1.9 A. The problems observed when this was attempted last week were due to an implementation error which resulted in an orbit error. With the current implementation there is no large tune change when changing the sextupoles (must have been an orbit error which put the beam off center (on average) in sextupoles). The tune change required to get back to our nominals near .41 are delta nu horiz ~.08 with delta nu vert ~.07. [Stan Pruss reports for these notes: The R64 tune trombone calculation to deduce dQx & dQy from the quad currents has been changed to use new fits centered around new operating point. This new calculation gives exactly the correct answer for dQx and gives .0819 for dQy when the correct value is 0.082. Before the newest fit this calculation gave .0736 for dQy. ] The change is working and we have about 85% injection efficiency for pbars (now!). Will transfer from a 50 mA Accumulator stack today. Want to put the dipole drive for the momentum change into the g(i) table. Stan warned that the inverse function on the tune trombone page is not sufficiently accurate with such a large tune change so caution is required. This calcuation will be addressed to achieve the desired accuracy. Brajesh Choudhary -- BPM Test Status Tests of the new digital down converter BPM electronics is underway. Brajesh provided the following summary. a. TESTS OF DDC BPMs needed. 1. Three bump scale and linearity measurement and comparison with the model. 2. BPM noise measurement. 3. Beam position stability over long time (hour, day) for stored beam. 4. Beam position stability for repeat injection (proper orbit closure). 5. Beam Position vs. Beam Intensity measurement. 6. Beam Position vs. Injection Phase Error measurement. 7. Position of 2.5 MHz beam with a large amount of debunched beam nearby. 8. Position of debunched beam in the barrier bucket, leading and trailing edges. 9. System sensitivity over a large range of RF voltage (Beam Position vs. Bunch Width measurement without barrier bucket). 10.Test the transient response besides moving phase and TBT measurement. b. The tests which have already been done: 1. Three bump scale and linearity was measured. It agrees with the MAD model. 2. BPM noise was measured for the beam intensity of 1E10 to 40E10 and the measured noise is within the specified range. 3. The beam position was found to be stable over long time (about 100 minutes) for the stored beam. 4. The beam position was found to be stable within rms for repeat injection at different beam intensities. 5. Beam Position vs. Injection Phase Error was measured and it was found that the beam position is not very sensitive to slow & small phase change. 6. System sensitivity was measured over a large range of RF voltage and the system was found to be insensitive to a large voltage change. c. Tests Still To Do: 1. Beam based alignment using MI-60 powered quadrupoles. 2. Position of 2.5 MHz beam with a large amount of debunched beam nearby. 3. Position of debunched beam in the barrier bucket, leading and trailing edges. (After MDAT system is incorporated) 4. Test the transient response besides moving phase and TBT measurement. Following the status report, there was an extensive discussion of the budget limitations and the merits of developing a plan which installed only a portion of the new electronics in FY03. Shekhar Mishra -- Reviews and Plans The DOE review went well. Thanks to all who prepared presentations. Vacuum upgrade plans are being pulled together by Peter Limon. We are planning to utilize the 3 week shutdown in January 2003 but the schedule is driven by the Lambertson magnet replacement in the C0 area of the Tevatron (using MI Dipoles). Several of the vacuum projects will be carried out in January. Shekhar Mishra -- Dampers One problem for the transverse dampers which must be resolved is the low frequency response of the amplifiers. The longitudinal damper plan needs to be documented. Design issues such as the modes which will be addressed, the hardware to be used, etc. need to be described. Peter Limon asked for a time frame. Bill Foster replied that they are looking to the end of January. We must resolve the capabilities of existing hardware due to the lead time for new hardware. It is believed that the problems are seeded by the beam properties delivered by the Booster. Elliott McCrory is new head of the Proton Source Department, replacing Bob Webber. We will have to learn who will be taking responsibility RF issues in the Booster. Progress has been made in resolving reporting of longitudinal effects between MI and TeV groups. The MI correctly calculates the RMS bunch length directly from the measurements and reports a bit more than 3 eV-sec. The TeV group fits to a Gaussian and reports the RMS as the fit parameter. The report just less than 4 eV-sec. This 30% descrepancy is understood now. There is not yet a plan for a consistent data analysis. The Division plans call for improvements in the longitudinal emittance delivered to the Tevatron by June 2003. If no hardware in the tunnel is needed, big improvements may be obtained by the end of January 2003. Beam loading compensation as well as the dampers may be required.