Tevatron Studies

End of Store   |   Ready to Go   |   Needs Thought   |   Low Priority   |   Mostly Completed   |   Completed All studies should have a time estimate and a person "in charge".

• scraping studies -- 2 hours -- Dean Still
  Look at alignment of collimators with the beam
• Tune Meter studies -- 1-2 hours -- C.Y. Tan
  Turn on T:HTICA and T:VTICA and adjust the power levels to try to find settings where we can see the pbar tunes without excessively blowing up the pbar emittances.

• Pbar injection efficiency - At present, with either uncoalesced or coalesced reverse protons, we get transmission efficiencies of about 95% from the Tev to the MI. With forward pbars we only get about 70-80% transfer efficiencies. To investigate this, we could try artificially blowing up the protons by mis-tuning injection (either increasing their transverse emittances with steering errors and/or their longitudinal emittance by an injection phase error). We could then see how the increased emittance affected the transfer efficiency.
  Also, IF there's an optics or dispersion mismatch, then reverse protons are NOT the same as forward pbars. (Reverse protons would be "extending" the Tev optics through the A1 line to MI, forward pbars would be "extending" the MI optics through the A1 line to the Tev.)
• As an attempt to improve the pbar lifetime at 150 Gev, try increasing the size of the helix at 150 Gev. The size of the vertical separation may be limited by the C0 aperture, but we may be willing to accept a worse proton lifetime. This will probably require some re-tuning of the feed downs at 150 Gev.
  If this helps at 150 Gev, we may also consider increasing the size of the helix at 162 and 180 Gev as an attempt to reduce the pbar loss there.
• Work on the pbar loss at about 80 sec into the squeeze, as we make the transition from the injection to the collision helix.
  1) Maybe just speed up this transition. Reduce the dt's for these steps from 5 sec to 1-2 sec.
  2) At present, we just linearly interpolate between the separator settings for the injection and the collision helices. Bagley will take another pass at the transition and try to find better intermediate settings.
• Investigate the problem with the "Revert to Proton Inj" aggregate.
• Check/Adjust (tune, coupling, chromaticity) values in the Proton Injection ramps. -- 2 hours -- Tev coordinator or on call person
  This could be done parasitically during shot setup.
• Tune Meter studies -- 1 hour -- C.Y. Tan
  At 150 Gev, turn on T:HTICA and T:VTICA and adjust the power levels to try to find settings where we can see the pbar tunes without excessively blowing up the pbar emittances. A good time to do this would be with a pbar pilot shot stored in the Tev.
• Tune drift at 150 Gev and F0 position -- about 4-6 hours -- Tev coordinator or on call person
  See brief studies plan in the Tev folder in the MCR.
• Now that the alpha* bump tuning is complete -
  
  • Repeat the one bump measurements at low beta (maybe also at 980 Gev and at 150 Gev). This is to check that the alpha* bumps behaved properly and did NOT make beta waves in the arcs.
  • Investigate the quadratic dependence of the vertical tune on the vertical one-bumps seen in the previous one bump measurements. Maybe try to "localize" the source of this.
  • Repeat measurements of the effect of the phase bump knobs on the tunes. This was last done on Oct. 28, 2000 when we had NOT yet corrected the beta waves in the arcs.
  • Do careful 5 point measurements of the chromaticity at 150 Gev, 980 Gev in the injection lattice, 980 Gev at low beta. This is to see if the alpha* bump tuning had any effect on the quadratic component of the tunes vs RF freq.

• We've had problems with the D0 proton losses (C:D0PHTL) during stores. These have been rather high and are only slightly affected by the collimators.
• During stores, CDF has had trouble with high rates in some of their muon chambers, presumably from beam halo.
• "Extra" Lines in Tune Spectra at collisions
  These may sometimes appear at 150 Gev as well. They only seem to be present when we have beam, but they could still be an instrumental effect. These lines tend to move around in frequency. When they are close to the tune lines, they can make the tunes look self excited or coherent. Generally when this happens, it does NOT seem to do bad things to the beam (lifetimes stay ok, emits don't blow up). At the moment, these don't seem to be causing real problems.
• MI Fly spec to look at individual Pbar bunches. -- Mostly parasitic -- MI personnel
  I believe the present MI fly spec for pbars looks at all 4 pbar bunches together. We would like to be able to look at each of the 4 pbar bunches individually to see if there are bunch to bunch differences in the MI.
• Orbits through B0 and D0. This refers to closed orbit bumps of both beams.
  There are several issues that come into this :
  1) We must keep the nearby correctors at reasonable strengths, including leaving room for tuning.
  2) The experiments must be satisfied with the positions and angles through their detectors. They will probably be concerned that the angles are nearly zero, but will be satisfied as long as the positions don't move.
  3) We would like to be centered in the low beta quads.
  Any one of these three can be used to set the correctors. Any actual setting of the correctors will be a compromise between these.
• Get rid of the dry squeeze between stores.
• Tune Meter Studies ??
• "Slow response" of BPMs to separators ?? - See data from Jun 20th, 2001.

• Electron Lens -- 1 shift -- Vladimir Shiltsev
  They have a standing request for 1 shift periods.
• Look at Photomultiplier signals for Flying Wires -- 8 hours -- Church
• Optics Match between A1 Line and Tev. -- ~2 hours ? -- Tev coordinator or on call person.
  The problem is the observed emittance blow up (according to MI Flying Wires) for "round trip protons" during reverse injection. On Jun 21st, during reverse injection, the proton vert emits were measured as 10 pi (MI, $2B) to 22 pi (Tev) to 16 pi (MI, $2A). As a first look at this, I think we should look at the effects of 1 bumps in the Tev on the trajectories back through the A1 line and into the MI. We can compare these to what we expect for the design optics to try to find quad errors. I don't know if this will be sensitive enough, but it is something to try. On July 5th, Bruce found that the A1 line multiwires were all IN. On July 6th, we repeated the "round trip" emittance measurement and found that we were only blowing up the proton vert emits by about 2-3 pi. This is small enough to make this a low priority.
• Optics Match between P1 Line and Tev -- 2 hours ? -- Tev coordinator or on call person
  This is not a priority, but is something we should eventually check.

• Separator Scans at the IPs - Change A17 Vert polarity ??
• E48 Kicker Timing -- The problem is that the first pbar bunch in the train of four has a very different injection oscillation and ends up with a bigger emittance. The timing adjustments from June 29th seem to have largely fixed this.

Updated: 14-Jan-2002

minor rev. 31-May-02