Recycler Status and Plans

Shekhar MishraMID/Beams Division

Fermilab

AAC Review 2/4/03

• Introduction to the Recycler Ring

• Recycler Improvements and status

• Jan 03 Shutdown work

• Summer 03 Shutdown work

• Study and Integration plans

• Summary

Introduction to the Recycler Ring

• The Recycler Ring is designed to store and cool antiprotons at 8.9 GeV/c. In the final configuration it may also Recycle antiprotons from the Tevatron at the end of store.

• The Accumulator stacking rate decreases as the stack size in the Accumulator increases .

Accumulator Antiproton Stacking (9/23/02)

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• An initial stacking rate of about 13e10/hr has been achieved in the accumulator.

• Transfer of antiprotons from Accumulator to Recycler will be done at small stack sizes, 30-60e10 to keep the stacking rate in the Accumulator high.

Recycler Study and (Upgrade) Goals

Goals

Number of stored antiprotons 2e12 (5e12)

Transfer efficiency(AccRR) >95%

Stacking efficiency(AccRR @1e12) >90%

Lifetime (2e12) (hrs) 100(200-300)

Equilibrium Normalized Emittance <10 pi mm-mr

Emittance Growth rate ~2 pi mm-mr/hr

Antiproton Recycling Efficiency >50%*

Longitudinal Emittance <54 eV-Sec

* This will depend on the emittance of beam at the end of store.

Recycler Upgrades (Since initial installation till Jan 03)

• Recycler End shim replacement

• Removal of magnetic heater tapes

• Alignment of beam pipes and BPMs

• Removal of high beta insert

• Realignment of All Recycler magnets with new fudicial.

• Install electromagnetic dipole correctors at each half cells, additional quadrupole and sextupoles.

• Install new magnetic shielding.

• Install new heater tapes inside each CFM and on beam pipes.

• Install new calibration circuit for all BPMs and calibrate every preamps.

• Install two scrapers and a new longitudinal Schottky detectors

• Install remote movable Stochastic cooling tanks

• Perform test on two vacuum sector by doubling Ion Pump.

Recycler StudiesDuring last several months the Recycler studies have addressed on the following topics

• Injection

• Efficiency of protons and antiprotons

• Emittance growth at injection

• Aperture

• Recycler Central Momentum Adjustment

• Recycler Lattice

• Beam Lifetime

• Antiproton transfer to the Recycler and stacking

• Commissioning of the cooling system

• Rf manipulation of beam

• Studies related with planed upgrades

Recycler efficiency

Loss at extractions points are due to injection error in the downstream machine and blowup of beam due to windows in transfer lines.

MI Reverse Tune-up using 53 MHz

Before tuning. After tuning.

• We have now installed a 2.5 MHz Beam Line Tuners in RR and MI to reduce injection oscillation. (Nov 02)

Horizontal Aperture

• After powering all the dipole corrector power supplies a new aperture scan was done.

• Installation of feed down sextupoles was done.

• We measured the horizontal aperture to be about 50 pi mm-mr.

• Vertical aperture is about 40 pi mm-mr.

Aperture after momentum adjustment

18.4 mm

BLM startsseeing loss

Longitudinal Schottky SA zero span video output sees extinction point (beamcenter)

Aperture ~60 pi mm-mr (H) ~40 pi mm-mr (V) on central orbit

MI Magnetic Field effect on RR orbit

A R&D on shielding revealed that we needed new mu-metal

and wrapping technique. Old shielding was not very effective.

But the motion in dp/p and tune is causing longitudinal and smalltransverse emittance growth.This will require an active correction.We plan to add more shielding during next shutdown. We are alsolooking at feed-forward and feedback techniques.

Active MI Ramp Correction Jan 03

Green trace with compensation on, rest off

Compensation on start at Green and stay on

This work is very preliminary, room for improvement. No tune compensation yet.

RR Lattice functions

Recycler DispersionHorizontal Beta

Antiproton transfer to Recycler

>95% circulating efficiency for 1st injection.

>75% stacking efficiency.

Recycler Proton Lifetime

• Unscraped proton beam lifetime 13 hours with Main Injector ramping.

• The aperture does not fill for 2 to 3 hours with Main Injector ramp.

• This is considerable improvement as compared to less than a minute aperture filling after

• We installed all the sextupole feed down correction (Aug 02)

• Complete scan in both H and V planes and centering the beam in aperture.

Pbar Heating and Cooling Rates

Measurement Method Beam Xe11 Result pi mm-mr/hr

Horizontal Cooling

Scraping 1.8-2.4 12

Vertical Cooling

Scraping 1.8-2.4 19

Transverse Cooling

IPM 7.5 15

Horizontal Heating

Scraping 1.8-2.4 4

No MI Ramping

Vertical Heating

Scraping 1.8-2.4 6

• Latest number with MI ramping: Heating rate 8 pi mm-mr/hr and cooling rate is 22 pi mm-mr/hr. 3.2e11 pbar in stack.

Emittance of the Cooled antiprotons

Measured emittance is about 7 pi mm-mr.

We have measured emittance of about 6.5 pi mm-mr in both planes for about 6e11 pbar in the stack.

This measurement will be repeated with more calibrated instrumentation and higher stack size.

Cooled antiprotons

• Transverse Emittance is about 7 pi mm-mr at a stack of 75e10 pbar. IPM needs study. It measurement is larger by x2 in H plane than size measured by scraping the beam.

pbar from Recycler to MI and Acceleration

Pbar from Recycler to TeV

~25-40% of the extracted pbar from RR circulated in the TeV.

Pbar lifetime

7 hours of store, 105 hours of lifetime for 0.75e12 antiproton.

36 hours store, 0.35e12 pbar, 180 hrs lifetime, 60 hrs improvement over past measurement at same intensity

Lifetime ImprovementsLifetime of pbar after 12/27/02

y = -0.4409x + 183.26

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Lifetime Linear (Lifetime)

Recycler Lifetime till 10/02

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Lifetime Linear (Lifetime)

The lifetime has improved due to cooling upgrade, tune up aperture improvements and MI ramp compensation.

Effect of vacuum on pbar lifetime

Lifetime improved from 90 hours to 125 hours after improving the MI30 sector vacuum by firing TSP.

Proposed vacuum upgrade will improve this considerably.

Physics Issues• Injection and circulating Efficiency for proton and pbar is about 90%

• Emittance growth is about a factor of 2-4 larger than the design. Significant fraction of this appears to be vacuum related.

• Recycler performance is adversely affected by the Main Injector ramp.

• Circulating and injection lattice and aperture

• Operating point of the Recycler is sensitive to the Recycler orbit.

• Cooling needs further study and optimization.

• RF manipulations need further study and optimization.

Recycler StatusIntegration Goal Achieved

Number of stored antiprotons 2e12 0.9e12

Transfer efficiency(AccRR) >90% 83%

Stacking efficiency >85% 75%

Lifetime (2e12) (hrs) 100 105*,180* (.7e12,.4e12)

Equilibrium Normalized Emittance <10 ~7* (0.5e12) pi mm-mr

Emittance Growth <2 ~ 5 pi mm-mr/hr

Longitudinal Emittance (eV-Sec) <54 75

* The Stochastic cooling system upgrade (equalizers), aperture improvements etc. This performance is expected to improve.

Jan 03 Shutdown work• Removed vacuum window from the R22 and R32 beam line installed differential pumping station.

• Rework the R30 straight section adding additional ion pumps and TSP's. We also added a Ecool segment in the Recycler ring for test purposes.

• Added Horz and vert schottky detectors into the Recycler at the 620 and 621 regions.

• Added Horz and Vert flying wires to the Recycler Ring at the R62 region.

• Removed some 400 ft old heater tape from magnets in the Ring/Transfer lines.

• Completed installation of Poly inserts ring wide to bake at higher temp.

• Upgraded nearly 40%+MI30 of the Ring with new ion pump assembly.

• Remove out of plane BPMs preamp in the for future upgrade.

• Removed and reinstalled some 8,000 feet of shielding.

• Fired TSP ring wide.

No vacuum Window in transfer Lines

There were 0.003” Ti window in both transfer line. This was the cause of ~35% emittance growth/window.

R30 straight section adding additional ion pumps and TSPs

This upgrade makes RR30 vacuum sector uniform with more TSPs, ion pumps and gauges. 6 RGA added to whole ring.

Horz and Vert schottky detectors into the Recycler

Horz and Vert flying wires to the Recycler

Now with Schottky Detectors, Flying wires and IPM we can make reliable measurements of beam emittances.

Technical Issues• Instrumentation Upgrades

• Beam Position Monitor (R&D in progress)

• Beam Line Tuner (Commissioned during Nov 02)

• Flying Wire (Installed during Jan 03 shutdown)

• Ion Profile Monitor (Physics Understanding needed)

• Schottky Detectors (Installed during Jan 03 shutdown)

• Injection Damper

• Reliable, calibrated and operational Instrumentation

• RF power and manipulations for injection, stacking and extraction

Technical Issues… Pbar transfer between machines

• The momentum and frequency was different between the Accumulator and Recycler.

• We have adjusted the Recycler momentum by using newly installed electromagnetic correctors in the Recycler.

• This has resulted in a large change in Tune of the Recycler. Which we are compensating by phase trombone. It was not designed to make this size correction.

• Frequency error is being taken care by the Main Injector.

• We may have to make further modifications to the Recycler to handle this issues in a better way.

Mechanical Upgrades of the Recycler• Vacuum upgrades (Expect to get x2 improvement in lifetime)

• Double ion pump in the Recycler

• Install insulator inside the CFM for higher temperature bake.

• Bake at a higher (>110 deg C) temperature for 4 days.

• Install more gauges and RGA

• Find and eliminate small leaks

• Lattice Upgrade of the Recycler

• Remove stuck old magnetic heater tapes from 24 magnets

• Additional quadrupole correctors

• Additional Magnetic shielding at select locations

Recycler IntegrationWe have started working on the integration of the Recycler into the Accelerator complex.

• Stack efficiently, reasonable lifetime and emittances.

• Re-bunch cooled beam in 2.5 MHz, transfer to MI and accelerate in MI to 150 GeV with >90% efficiency, using 53 Mhz.

• Develop 2.5 MHz acceleration in MI through transition to eliminate coalescing of beam at 150 GeV.

At start this has to break even with Accumulator stacking and show potential of improvement

• If the stacking rate in the Accumulator improves to 15e10 pbar/hour.

• Similar or better emittance of the beam to Tevatron.

• 1.5e11 pbar/hour

• Transfer every 3 hours

• Recycler shot setup 30 mins.

• 2e12 in 20-24 hours, depending on stacking efficiency at large stack size.

Simulated Recycler Stacking

• This calculation assumes slightly improved Recycler performance in stacking efficiency of 85% and present intensity dependent lifetime.

• It is compared with a calculation where lifetime of 100 hours and 300 hours at 2e12 with small intensity dependence.

Recycler stacking (15e10 production)

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Recycler Stack (300 hours lifetime at 2e12)

Summary• Over the last year we have made significant progress in the Recycler performance.

• Recycler circulating antiproton beam efficiency >95% and stacking efficiency of about 75% has been achieved.

• Antiproton lifetime >100 hours for >75e10 pbar.

• We still have several issues related to RF manipulations at stacking and extraction.

• We have proposed several upgrade to improve the performance of the Recycler.

• Recycler is close to being a machine which can be integrated into the complex.

• The proposed Recycler upgrade will make the Recycler fully operational.