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Maximizing Tevatron Collider Performance with Nova Integration

Explore running Tevatron Collider alongside Nova, utilizing Recycler for maximum luminosity. Learn about upgrades enhancing proton beam power for both projects.

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Maximizing Tevatron Collider Performance with Nova Integration

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  1. How to Run the Tevatron Collider with Oodles of Luminosity and Send Gobbs of Protons to NoVa at the Same Time Dave McGinnis April 15, 2010 Run III - McGinnis

  2. Introduction • After the results of the LHC Chamonix workshop were published, a few of us at Fermilab started wondering : • does it makes sense to run the Tevatron longer than planned? • maybe until 2015? • We realize that the Recycler, which is a key component for the collider, is going to be cannibalized for Nova starting in 2011-2012 • We wonder is there any way to run the Tevatron and Nova at the same time? • That’s the whole point of this talk. Run III - McGinnis

  3. The Informal Organization • Physics case of Run III • State of the detectors • State of the accelerator • Luminosity in the Collider • Protons for Nova This talk Hmmm.. Run III - McGinnis

  4. State of the Tevatron Collider • The Tevatron Collider is operating at its peak performance. Currently: • The average yearly integrated luminosity exceeds 2fb-1. • The average weekly integrated luminosity exceeds 50pb-1. • The average peak luminosity is over 300mb-1/sec. • The Tevatron spends over 130 hours per week in colliding stores. Run III - McGinnis

  5. Tevatron Collider Performance Run III - McGinnis

  6. State of the Tevatron Collider • It is often stated that the Tevatron Collider complex is an ``aging machine,’’ • to imply that continued operations would be “a priori fragile”. • This is simply not the case. • Tevatron performance parameters continue to climb. • The store hours per week have risen dramatically over the years, from 70 hours per week in Run I to over 130 hours per week in Run II. • While every machine of this complexity needs constant maintenance • The overall outlook on maintenance and spares for the Tevatron, Main Injector, Recycler, and Antiproton source has remained unchanged for at least the past three years. Run III - McGinnis

  7. Role of the Recycler in the Tevatron Collider • Since the Tevatron is a proton-antiproton collider • it is limited by antiproton beam brightness. • The spectacular performance of the Tevatron Collider • is the culmination of many years of investment into the Main Injector, Recycler, and Run II upgrades • that substantially increased the antiproton beam brightness. • One of the major components of the Fermilab antiproton production capability is • the Recycler and its electron cooling system. Run III - McGinnis

  8. Role of the Recycler in the Tevatron Collider • The Recycler functions as a third stage storage ring for antiprotons • which reduces the load on the rapid stacking with stochastic cooling in the Antiproton Source. • Electron cooling in the Recycler, • which was considered by many as risky when it was first proposed. • condenses the antiproton beam to unparalleled beam brightness. • Without the Recycler and electron cooling, • experts estimate that the yearly integrated luminosity would be halved from its current level. Run III - McGinnis

  9. Planned Accelerator Upgrades for NoVa • At the end of the collider run: • Electron cooling will be decommissioned • The Recycler will be turned over to the neutrino program to act as a proton accumulator for the Main Injector. • The conversion of the Recycler to a proton accumulator is just one of a suite of upgrades to the accelerator complex for the neutrino program. Run III - McGinnis

  10. Planned Accelerator Upgrades for NoVa • 1. With the use of the Recycler as a proton accumulator, the Main Injector cycle time can be decreased substantially. • The reduction in Main Injector cycle time provides a 44% increase in 120 GeV beam power. • 2. The Recycler can also accommodate one more Booster batch than the Main Injector current does for slip stacking. • The extra batch would increase the beam power by 11%. Collider and Nova - McGinnis

  11. Planned Accelerator Upgrades for NoVa • 3. Once the collider is no longer running, the two antiproton production batches per Main Injector cycle can be allocated to the neutrino program • which yields another 20% increase in beam power. • 4.Upgrades to the Main Injector power system will permit a faster Main Injector energy ramp • yielding another 15% increase in beam power. • With these changes, the maximum Main Injector 120 GeV beam power will be 700kW. Collider and Nova - McGinnis

  12. Planned Accelerator Upgrades for NoVa Collider and Nova - McGinnis

  13. Proton Economics Run III - McGinnis

  14. Making Protons • To make lots of protons you need • longitudinal phase space • longitudinal phase space density • Making longitudinal phase space is easy but expensive. • This is why we chose the Recycler. • It has tons of longitudinal phase space and nobody else wanted it • So using it as proton accumulator is a "no-brainer". • Increasing longitudinal phase space density is • usually more difficult  • usually less expensive. Run III - McGinnis

  15. 120 GeV Beam Power Without the Recycler • As noted earlier, once the Recycler is re-commissioned for the NoVa program, it will be difficult to run Tevatron without a severe drop in luminosity. • By taking advantage of the otherNoVa upgrades to the Main Injector, it is possible • To keep the Recycler dedicated to the collider • And provide a 55-75% increase in Main Injector 120 GeV beam power over the present 320kW level Collider and Nova - McGinnis

  16. 120 GeV Beam Power Without the Recycler • 1. Faster Main Injector Cycle time yielding an 18% increase in beam power. • Faster ramps using the upgrades to the Main Injector power system • shorter flattop dwell times • eliminating deceleration energy ramp parabolas • 2. Allocate all of the currently available Proton Source Flux to NoVa and the collider programs • Stage 1. Increase the proton source batch intensity by 18% (11x1016 protons/hour – current Booster limit) • Stage 2. Increase the proton source batch intensity by another 13% (12.2x1016 protons/hour) • 3. Interleaving the antiproton production pulses to every other Main Injector ramp cycle will increase neutrino flux by 11%. Collider and Nova - McGinnis

  17. Proton Economics Collider and Nova - McGinnis

  18. Notes on Antiproton Production • The interleaving of antiproton production pulses reduces the proton flux on the antiproton production target • This would seem to cause a significant drop in the antiproton accumulation rate. • However, the antiproton source stochastic cooling becomes more efficient with the longer antiproton cycle time that would occur with interleaving. • Also since the antiproton uses only 10% of the proton source flux, • The proton source batch intensity for antiproton production can be increased substantially • With a negligible effect on the total proton flux. • The net reduction in antiproton stacking rate would be only 12%. Collider and Nova - McGinnis

  19. Tevatron Adjustments • The reduction of 12% in antiproton production rate would create a corresponding reduction in collider luminosity. • The reduction in luminosity can be compensated by increasing the number of protons at collisions. • To increase the number of protons at collision in the Tevatron, the Tevatron betatron tune working point would have to be moved. • The circuits for doing this are already in place. • The concept has been thoroughly worked out. • For implementation, study time would have to be allocated. Collider and Nova - McGinnis

  20. 120 GeV Beam Power Without the Recycler (Stage 1) • The 120 GeV beam power for Stage 1 would be 500kW which is 70% of the 700kW. • Stage 1 requires no additional cost beyond what is already allocated for NoVa • Stage 1 does not require the Proton Source to provide more flux than it currently is delivering. Collider and Nova - McGinnis

  21. Comments on Proton Flux • The Booster is the bottle-neck for proton flux at the Fermilab complex. • Hence the desire for Project X • The limit is set by beam loss and tunnel activation in the Booster • The maximum flux that the Booster has produced is 11x1016 protons/hour. • Which is where the Stage 1 limit is set. • No upgrades to the Booster for continued Tevatron running are required Collider and Nova - McGinnis

  22. Comments on Proton flux • To run higher beam powers to NoVa, the Proton source would have to provide more than 11x1016 protons/hour • The limit is set by beam loss and tunnel activation in the Booster • One of the main causes of beam loss is longitudinal emittance dilution. • There are two ways to combat this: • 1. More RF voltage (i.e more RF cavities) for bigger buckets • Straightforward solution • Expensive solution • 2. Reduce longitudinal emittance dilution • Better capture • Better damping • Space charge compensation with transverse phase space painting • These are cheaper cures – but more risky. Collider and Nova - McGinnis

  23. Comments on Proton Flux (continued) • There are many other projects that can be done in the Booster • More reliable RF power (solid state amplifiers) • Better Booster - MI cogging system (faster kickers) • Better orbit control (more ramp break points) • Bigger aperture (magnet moves) • Better tune control • Transverse dampers • Better longitudinal dampers (more bandwidth) • Better collimation (primary collimation) Collider and Nova - McGinnis

  24. Proton Economics Collider and Nova - McGinnis

  25. Summary • By taking advantage of the NoVa Upgrades to the Main Injector • it is possible to deliver at least 500kW of beam power to Nova • Without asking for more proton flux from the Booster than is currently available • Run the collider at the current level of luminosity Collider and Nova - McGinnis

  26. Booster Intensity Backup Slides Collider and Nova - McGinnis

  27. Main Injector Cycle Time • The NoVa upgrades to the Main injector is to install a new quad bus power supply and add two more RF stations. • This brings the cycle time to 1.33 seconds.  • The 1.33 second ramp includes • a 0.08 second 8 GeV dwell time • a 0.05 second flattop dwell time • two deceleration parabola's of 0.1 secs each.   • This accounts for  0.23 extra seconds • using only 1/2 of the parabola time • Looking at the regulation plots during the dwell times • the dwell times can be reduced • because there is plenty of bucket area at 120 GeV, flattop bunch rotation can be started during acceleration. • Also the deceleration parabola's can reduced or eliminated. • To go from 1.33 seconds to 1.2 seconds 0.13 seconds are eliminated by shortening the dwell times and deceleration parabola's.  Run III - McGinnis

  28. Slip Stacking Efficiency • The Booster longitudinal emittance and transverse emittance does not grow linear with intensity. • The Booster longitudinal emittance is dominated by instabilities • With the Booster longitudinal dampers, the longitudinal emittance is fairly flat over a wide range of intensity. • The slip stacking loss is from DC beam not captured in the in the final bucket. • This is a fairly intensity independent effect • no instabilities in the Main Injector • there is plenty of overhead in the RF power amplifiers for transient beam loading compensation. • Therefore slip stacking efficiency should be fairly constant with intensity Run III - McGinnis

  29. Booster Beam Intensity • The Booster routinely accelerates 5.3e12 with 93% efficiency for Tevatron fills • The efficiency for 4.3e12 is on the order of 94%. • To run 11e16 at 4.3 e12, the average Booster rep rate is 7.1Hz. • To run 500kW to NoVa, the Booster needs to run 5.1e12 at 5.9Hz. • This corresponds to a 15% increase in beam loss in the Booster tunnel. • Note that to do NoVa at 700kW, 27% more power is lost in the tunnel than is currently done at 11e16/hour.  • We assuming some improvement with • transmission increase with the new RFQ • higher RF voltage due to the reliability brought by the solid state RF upgrade. • Since there will have to be a lot of work done to get to 14e16/hour in the Booster, we are also assuming that Booster losses will decrease in the future. Run III - McGinnis

  30. Event $15 Operations Charge on shot to Tev. Intensity @ 5.25 and 93% efficient (No Notch on these cycles) Red is collimator loss Yellow is loss below BWT 5.0 3.0 4.0 1.5 3.0 0

  31. Antiproton Stacking Timeline • Since the Debuncher cooling is power limited • it is better to send a high intensity pulse at a slower cycle time • than a low intensity pulse at a short cycle time. • The scenario is to interleave stacking pulses every other Main injector ramp cycle. • For example, on Main Injector Cycle A, • 11 batches go to NoVa, • 0 go to pbar. • On Main Injector Cycle B, • 9 batches go to NoVa, • 2 go to pbar Run III - McGinnis

  32. Antiproton Stacking Rate • The Booster batch intensity for antiproton production goes from 4.5e12 to 5.5e12.  • The cycle time goes from the present 2.2 to 3.73 seconds. • This looks on surface like a 30% drop in flux. • The longer cooling time helps dramatically. • By increasing the cycle time to 3.73 seconds, the antiproton production efficiency should rise from 21e-6 to 30e-6 for the same number of protons on target. • Since the number of protons on target is increasing, the gain in production efficiency is de-rated the production to 26e-6. • Since the Debuncher cooling is power limited, this is a conservative estimate. • The Stacktail cooling system is in between power limited and gain limited, so the production of 26e-6 is justified Run III - McGinnis

  33. 5.6E12 @ 91% (No Notch) 6.0 Plot of Charge (green) Plot of loss at collimator (red) Plot of loss below BWT (yellow) 5.0 4.0

  34. The Tevatron • The change in working point concept • has been around for a long time since first pushed by Lebedev and Shiltsev. • has been thoroughly worked out by Valishev. • The luminosity integral is proportional to the number of protons. • Pushing the Tevatron tune closer to the 1/2 integer • as is done at the B-Factories • will give up to  50% more tune space than is currently obtained • which implies that the proton intensity can be increased by up to 50%. • We are asking to increase the proton intensity by 12%. • Complex luminosity evolution simulations • that takes into account emittances, long range effects, etc., • Showed that the luminosity integral lost by reduced stacking rate can be completely recovered. Run III - McGinnis

  35. Tevatron Working Point Scenarios Run III - McGinnis

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