Electron Cooling in the Recycler Ring Alexander Shemyakin (Fermilab/AD) May 31, 2005.

Electron Cooling in the Recycler RingAlexander Shemyakin (Fermilab/AD)May 31, 2005

Tevatron luminosity and antiprotonsThe Tevatron luminosity is linear with the total number of antiprotons available for the Tevatron store. The antiproton beam quality is characterized by the phase-space density. To achieve higher luminosity this density needs to be increased.

Fermilabs antiproton production chainInconel targetDebuncher (stochastic cooling)Accumulator (stochastic cooling)

8 GeV8 GeVUntil 2005Electron cooling in the Recycler Ring eliminates one of the bottlenecks in the long chain of the antiproton production. is the relative phase-space density

Idea of Electron coolingThe idea of electron cooling is a heat exchange through Coulomb scattering between hot heavy particles (antiprotons) and cold electrons while the beams are mixed in a cooling section.Was invented in 1967 by G.I. Budker (INP, Novosibirsk) as a way to increase luminosity of p-p and p-pbar colliders.

First tested in 1974 with 68 MeV protons at NAP-M storage ring at INP (Novosibirsk).CERN- ICE 1977 1979Fermilab 1979 - 1982

Low energy coolersWell established techniques for electron energies below 300 keV.A strong, continuous longitudinal magnetic field from the gun to the collectorAn electrostatic accelerator working in the energy- recovery modeExample of a 300 keV, 3 A cooler produced by Budker INP for IMP, Lanzhou (China). The voltage difference between the gun and collector ~ 3 kV.

Difficulties of implementing at relativistic energiesHigh electron beam power:4 MeV * 0.5 A = 2 MW DC!

Beam quality:The electron beam temperature (in the rest frame) should be comparable with the cathode temperature of 1200K (only a factor of ~10 increase is allowed for the transverse degree of freedom)

Design parameters of the RR ECool beam

Energy4.34 MeVBeam current0.5 Amps DC Angular spread0.2 mrad Effective energy spread 300 eV

History of relativistic electron coolingFermilab, 1983: D. Cline et al., Intermediate energy electron cooling for antiproton sources using a Pelletron acceleratorFor a pulsed electron beam in a Pelletron the beam quality is adequate for electron coolingNovosibirsk, 1987: successfully tested a prototype 1-MV, 1-A electron beam system.Continuous magnetic fieldAcceleration tubes are not sensitive to vacuum UVFermilab, UCLA, NEC, 1989: tested a 2-MV, 0.1-A DC recirculation system with a Pelletron.Poor stabilityFermilab, IUCF, NEC, 1995: started to work on a 2-MV Pelletron again- beginning of the RR ECool project

PremiseSolution for a high-power beam generator: use of a standard electrostatic accelerator (Pelletron) and non-standard focusing scheme Recirculation (energy/charge recovery) schemeNo continuous magnetic fieldA low-magnitude longitudinal magnetic field in the cooling section and at the cathode, but a lumped focusing in the remaining part of the beam line

Failure of the previous attempt was recognized to be caused by high losses in the acceleration tubesCurrent losses needs to be decreased below 0.01%

New solutions for the gun and collector were found. A gun with a negatively biased control electrode to suppress the beam halo and provide the beam transport at all currentsEffective suppressing of secondary electrons in the collector can be done by applying a transverse field in the collector cavity

Stage I - Test at NEC (Middleton, WI)GOALTo demonstrate a stable (~1 hour) generation of a 0.2 A relativistic beam using an existing 2 MV Pelletron at NEC

Nov. 95:project startedJan. 97:first recirculated current (10 A)Dec. 97:Max. recirculated current of 0.2 AMay. 98:0.2 A for 1 hours at 1.3 MeVDec. 98:Max. current of 0.7 AJan. 99:Gun solenoid (200 G) installedFeb. 99: 5 MeV Pelletron orderedMay.99:0.9 A with 200 G at the cathodeHow to scale the result for 1.3 MeV beam in a 2-MV tubes to a 4.3 MeV beam in a 5-MV accelerator ?

Stage II short line at WideBand Building (Fermilab)New means to improve stability: ion stoppers, crash scraper, closing the gun in 1 msDiagnostics: BPMs, scrapers, flying wireOperation was stable only at 3.5 MV. The tubes clearly needed to be extended. Now the main question was the beam quality.GOAL : To demonstrate a stable generation of a 0.5 A, 4.34 MeV beam in a short beam line

Feb 99: 5 MV Pelletron ordered.May 01: First beam of 30 A in the collector.Dec 01: 0.5 A at 3.5 MV Apr 02: NEC replaced acceleration tubesOct 02: 0.5 A at 4.34 MeVNov 02: Imax = 1.7 A at 3.5 MV Shut down to install the full beamline

Stage III full- length line at WideBandThe beam line was very similar to the final one at MI-31A novel type of the beam optics, angular momentum dominated Developed a technique of precise measurements of the solenoid field qualityBeam envelope measurements with movable orificesFinal version of BPM electronics

Jul- 03 - first DC beam in the full- scale lineDec-03- 0.5 A DC beamMay-04- 0.1 A beam with required properties in the cooling section

Final stage- Cooler in the RecyclerJun. 2004 Jan. 2005- assembling the cooler in MI-31/30Oct 2004- magnetic measurements in cooling sectionApr 2005- first DC beam in the collector passed through the cooling section

Difficulties (some of them) and solutionsFull dischargesImprovements in the protection system (closing the gun in 1 s)Minimizing current losses to acceleration tubes (dI/I

CoolingOne of the first indications of interaction between antiprotons and electrons. The plot shows evolution of antiproton energy distribution (log scale) after turning on an electron beam. Initially antiprotons occupy the entire momentum aperture of the Recycler.First interaction - July 9, 2005

First cooling- July 11, 2005

First electron cooling-assisted shot to Tevatron- July 12, 2005

Drag Force as a function of the antiproton momentum deviation100 mA, nominal cooling settings

First cooling rate measurements published

Electron cooling between transfers/extractionElectron beam is moved inStochastic coolingafter injectionElectron beam out (5 mm offset)Electron beam current 0.1 A/divTransverse emittance 1.5 p mm mrad/divElectron beam position 2 mm/divLongitudinal emittance (circle) 25 eVs/divPbar intensity (circle) 16e10/div~1 hour100 mA195e10~60 eVs254e10

Evolution of the number of antiprotons available from the RecyclerMixed mode operationEcool implementationRecycler only shots01/10/05 02/18/06

Chart1

42

47

85

90

91

54

56

78

67

74

89

37

37

45

45

49

49

91

91

72

71

71

69

70

71

71

86

86

81

81

68

16

57

48

78

64

85

92

98

91

43

76

65

70

63

56

124.1

113

166

51

74

58

39

108

60

116

90

138

124

121

143

144

44

66

138

94

56

69

58

14

16

59

7

33

32

42

45

49

47

65

52

128

85

51

59

74

43

71

95

30

90

32

62

106

83

53

100

81

58

61

60

94

109

51

46

92

137

116

111

Ecooling

59.5

90.7

30.6

85

48

100

60

100

143

126

59

59

89

85

92

81

97

116

112

137

111

182

46

41

98

110.5

143

60

109

64

70

136

70

113

165

129

134

141

142

216

241

90

55

69

77

225

280

235

257

183

153

209

117

197

228

111

168

191

219.57

223

285

247

266

320

220

256

89

171

248

204

200

300

248

252

174

99

132

77

181

72

55

163

219

288

236

137

270

255

273

260

354

326

323

289.7

284

198

154

115

127

182

30

107

176

201

139

209

181

334

258

258

418

197

131

150

283

166

243

Number of antiprotons (x 1010)

Sheet1

data

DateIntensityLong emittance 90%Long emittance 95%RMS mom spread90% mom spreadBucket lengthTrans emittanceNotes

2/14/041.88E+0114.018.215linear ramp, two bunches

4/7/041.60E+017.09.13.36linear ramp,single bunch

2/20/041.20E+0263.081.95.37Barrier bucket

3/12/043.50E+0121.027.32.37Barrier bucket

3/14/047.80E+0151.061.23.110.54.87Barrier bucket

3/25/043.57E+0131.938.32.89.23.33Barrier bucket

4/7/041.60E+017.09.23.511.70.36Barrier bucket

4/8/043.10E+0111.314.33.70.67Barrier bucket

4/12/045.20E+0120.625.6413.21.26Barrier bucket

4/23/049.70E+0149.058.83.110.34.64Barrier bucket

4/21/047.50E+0140.752.9

4/24/048.70E+0151.066.35.4

4/26/041.26E+0264.083.26

4/27/041.23E+0254.164.93105.33Before instability

4/30/041.17E+0250.060.03.110.34.74.2Barrier bucket

4/30/041.30E+0258.169.6310.25.73.6

5/3/041.45E+0263.876.53.210.65.854.3

5/28/044.33E+0116.319.72.58.41.855

6/9/046.70E+0130.837.23.311.12.65before mining for mixed mode

6/29/047.78E+0123.428.43.210.925Barrier bucket, before mining, after linear rf

7/6/047.50E+0123.028.03.411.61.85Barrier bucket, before mining, after linear rf


7/20/046.04E+0122.327.23.310.81.825.4Barrier bucket, before mining, after linear rf

7/20/04626234.5

7/21/04505023.1

8/5/04424220.9

8/11/04303018.8

8/12/04404020.3

From This Time on we started

12/29/046.62E+0118.928.02.9101.85Barrier bucket, before mining, after linear rf




1/15/05331414




1/27/054016.0





2/1/056.72E+0121.626.231024.2Barrier bucket, before mining, after linear rf




2/8/058.93E+0134.241.63.7612.42.464.5

TDR2.60E+0254.070.25538.547.75

6.50E+0254.070.25538.5125

1.80E+0254.070.25538.536.855

2.00E+016.07.85.854.0954.095

2.00E+010.00.0000

0.00E+000.0

1.80E+0296.0

6/30/047932

7/6/047728

7/16/049235.3

12/23/044120.9

12/29/046628

1/10/054220

1/12/054722

1/17/058536

1/18/059040

1/20/059143

1/24/055422.1

1/28/055627

1/30/057829

2/1/056726

2/3/057428

2/8/058941

2/13/053719

2/13/053718

2/17/0545

2/17/054522

2/22/054932

2/22/054932

2/23/059148

2/23/059144

2/24/057236

2/26/057130

2/26/057129

2/27/056939

2/27/057038

3/4/057135

3/4/057135

3/5/058640

3/5/058640

3/7/058140

3/7/058140

3/8/056837

3/9/05168.5

3/10/055728

3/12/0548

3/14/0578

3/15/056430

3/17/058543

3/18/059248

3/20/059847

3/21/059148

3/25/054323

3/26/057641

3/27/056530

3/29/057033

3/30/056328Started using ibs to help cool

4/2/055628

4/4/05124.147

4/7/05113.046.0

4/8/05166.059.3

4/10/0551.025.0

4/14/0574.031.0

4/17/0558.027.0

18-Apr39.019.0

4/20/05108.040.0

4/23/0560.028.0

4/24/05116.054.0

4/25/0590.035.0

4/27/05138.052.0

4/29/05124.045.0

4/30/05121.045.0

5/2/05143.052.0

5/4/05144.051.0

5/7/0544.020.0

5/9/0566.028.0

5/12/05138.051.0

5/13/0594.037.0

5/17/0556.022.0

5/18/0569.026.0

5/19/0558.024.0

5/19/0514.09.0

5/21/0516.010.0

5/23/0559.025.0

5/23/057.06.3

5/24/0533.014.0

5/26/0532.013.0

5/27/0542.018.0

5/28/0545.020.0

5/29/0549.024.0

5/31/0547.021.0

6/2/0565.028.0

6/4/0552.025.0

6/6/05128.051.0

6/7/0585.032.0

6/8/0551.035

6/10/0559.031.0

6/11/0574.030.0

6/17/0543.020.0

6/18/0571.030.0

6/19/0595.042.0

6/20/0530.014.0

6/22/0590.041.0

6/23/0532.014.0

6/24/0562.024.0

6/26/05106.045.0

6/28/0583.033.0

7/1/0553.023.0

7/5/05100.040.0

7/23/0581.026.0

7/26/0558.041.0

7/30/0561.025.0

7/31/0560.026.0

8/2/0594.041.0

8/7/05109.040.0

8/16/0551.025.0

8/18/0546.022.0

8/22/0592.044.0

8/26/05137.078.0

8/27/05116.078.5

8/29/05111.076.0

Ecooling

7/16/0559.515.9

7/18/0590.727.0

7/19/0530.68.5

7/21/0585.028.0

7/22/0548.019.0

7/25/05100.028.0

7/28/0560.020.0

8/1/05100.034.0

8/4/05143.051.0

8/6/05126.040.0

8/8/0559.018.0

8/10/0559.018.0

8/12/0589.024.0

8/13/0585.024.0

8/14/0592.028.0

8/18/0581.025.0

8/19/0597.035.0

8/23/05116.035.0

8/24/05112.031.0

8/26/05137.054.0

8/30/05111.037.0

9/1/05182.062.0

9/2/0546.018.0

9/3/0541.016.0

9/5/0598.030.0

9/6/05110.522.9

9/8/05143.036.0

9/9/0560.016.0

9/12/05109.028.0

9/13/0564.021.0

9/14/0570.021.0

9/16/05136.051.0

9/17/0570.027.0

9/18/05113.027.0

9/20/05165.067.0

9/22/05129.050.0

9/22/05134.047.5

9/24/05141.055.0

9/25/05142.049.0

9/26/05216.064.0

9/28/05241.065.0

9/28/0590.035.0

9/30/0555.020.0

10/1/0569.023.0

10/2/0577.028.0

10/4/05225.062.0

10/5/05280.060.0

10/8/05235.065.0

10/10/05257.066.0

10/12/05183.078.0

10/13/05153.051.0

10/15/05209.065.0

10/15/05117.032.0

10/16/05197.066.0

10/17/05228.066.0

10/19/05111.035.0

10/21/05168.057.0

10/22/05191.068.0

10/23/05219.657.0

10/25/05223.067.0

10/27/05285.067.0

10/29/05247.078.0

10/28/05266.066.0

10/31/05320.072.0

11/2/05220.071.0

11/3/05256.080.0

11/4/0589.045.0

11/5/05171.051.0

11/6/05248.065.0

11/7/05204.070.0

11/9/05200.070.0

11/10/05300.068.0

11/12/05248.065.0

11/13/05252.067.0

11/15/05174.055.0

12/12/0599.040.0

12/13/05132.060.0

12/14/0577.035.0

12/16/05181.058.0

12/17/0572.037.0

12/18/0555.028.0

12/19/05163.065.0

12/21/05219.063.0

12/22/05288.066.0

12/23/05236.064.0

12/25/05137.040.0

12/27/05270.065.0

12/28/05255.059.0

12/30/05273.065.0

1/2/06260.067.0

1/6/06354.072.0

1/7/06326.076.0

1/8/06323.070.0

1/10/06289.766.0

1/11/06284.068.0

1/14/06198.055.0

1/19/06154.061.0

1/23/06115.069.0

1/27/06127.074.0

1/28/06182.069.0

1/30/0630.049.0

2/2/06107.041.0

2/3/06176.041.0

2/4/06201.061.0

2/5/06139.040.0

2/6/06209.059.0

2/7/06181.090.0

2/9/06334.075.0

2/10/06258.055.0

2/12/06258.067.0

2/14/06418.066.0

2/17/06197.066.0

2/18/06131.054.0

2/19/06150.055.0

2/20/06283.058.0

2/21/06166.054.0

2/22/06243.059.0

2/1/06274.062.0

2/1/06240.043.0

Damper Test

8/23/0558.09.8

8/24/05112.024.0

now110.522.9

2.2222222222

7.5

data

00000

00000

00000

00000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

000

000

000

000

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Cons data

Pbar intensity, xE10

Long emittance (95%), eV-s

Recycler's best long. emittance as of 04/10/05

Plot

000000

000000

000000

000000

0000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Pink Line

Post IBS Cooling (3/05 - 8/05)

blue Line

Ecool (7/05 - present)

'Feb/04 - Dec/04'

Last 5 to Tev



Recycler's Long. Emittance with Electron Cooling

Sheet3

000

000

000

000

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

blue Line

Pink Line

'Feb/04 - Dec/04'



Recycler's Long. Emittance Pre IBS Cooling

0000000

0000000

0000000

0000000

00000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

000

000

000

000

000

000

000

000

000

000

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Pink Line

blue Line

Ecool (7/05 - present)

last 5

dec '05

Jan '06

Feb '06



Recycler's Long. Emittance as of 2/28/06

0000

0000

0000

0000

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Pink Line

Post IBS Cooling (3/05 - 8/05)

blue Line

'Feb/04 - Dec/04'



Recycler's Long. Emittance Post IBS Cooling

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Mixed Mode Operations

EcoolImplementation

Recycler OnlyShots

Number of antiprotons (x 1010)

Long emittance

14

63

21

50.9913654065

31.908509866

7.0404649281

11.2891480685

48.9543515619

40.7

51

64

54.1471258502

50

49.9728362532

58.0912629581

63.8191827374

16.3045085162

30.7541904285

20.6061774981

7

Remaining questionsLife timeThe antiproton life time suffers at strong electron coolingEffect is not dramatic, but its removal will add additional percents to the number of antiprotons in Tevatron

Ultimate strength of coolingECool works at 3001010 , but additional work may be needed to cool effectively 6001010.

SummaryThe relativistic, non- magnetized electron cooling has been demonstratedAllows other laboratories to proceed with further developments:BNL- electron cooling at RHIC, Ee= 54 MeVGSI & TSL- fast cooling of antiprotons, Ee= 4 - 8 MeV

Fermilab has a world record electron cooling system that has allowed recent advances in luminosity

A hard limit on the maximum number of antiprotons in the Recycler has been removed. The road to higher luminosities is open.

The team (at the final stages)Beam studiesA.BurovK.CarlsonD.BroemmelsiekC.GattusoM.HuG.Kazakevich (BINP, guest scientist)T.KrocS.NagaitsevL.ProstS.PrussS.Seletskiy (U.of Rochester)A.ShemyakinC.SchmidtM.SutherlandV.TupikovA.Warner

Engineering supportB. KramperJ. LeibfritzL. NobregaG. SaewertK. Williams

Technical supportM. FrettR. KellettJ. NelsonJ. Simmons

International collaborationBINP (Novosibirsk, Russia)V. ParkhomchukV. RevaCOSY (Juelich, Germany)D. PrashunBNLA. FedotovPhysics discussions and modelingV. Lebedev

JINR(Dubna, Russia)I.N. MeshkovA. SidorinANLW. Gai

Electron Cooling in the Recycler Ring Alexander Shemyakin (Fermilab/AD) May 31, 2005.

Documents

electron beam system

electron beam temperature

pulsed electron beam

electron energies

electron coolingnovosibirsk

beam transport

beam halo

beam linefailure