HESR Electron Cooler

COOL05Eagle Ridge, Galena, IL USA

September 18-23, 2005

D. Reistad, TSL

The Future International Facility at GSI:Beams of Ions and Antiprotons

UNILACSIS

FRS

ESR

100 m

SIS 100/200

HESRSuperFRS

NESR

CR

Existing Future Project

HESRHESR ‘flagship’ beam parameters

1

1

ε [mm mrad]

8 GeV

8 GeV

pbar Energy

10-5

10-4

∆p/pL [cm-2 s-1]Mode

2x1031High resolution

2x1032High luminosity

i8γt

7.5<ßx> [m]

3.5<Dx> [m]

570C [m]

HESR ring/lattice parameters

Number of antiprotons for aninternal target area density of 4x1015 cm-2:

HL mode: 1011 (0.8-14.1 GeV )HR mode:1010 (3-8 GeV)

PANDA @ HESR

• Hydrogen pellet target

• 2 cm diameter beam pipe!

WASA Pellet Target

• access and availability restricted

• development of the PTS !

Pellet Generation Principle

dropletformation

vacuuminjection

nozzle

capillary

H2

At WASA:

width of pellet stream: 2 mm

vertical separation of pellets: 3 mm

1

2

3

4 Radius [mm] 1 2

2.41

3.57

0.70

Distance [m]

Skimmer (inner diameter 0.8 mm)

CELSIUS beam

CCD-camera

Vacuum injection 0

PANDA needs a 2-3 mm big beam with 1010 – 1011

antiprotons with momentum spread 10-5 – 10-4, and without any halo.

This can not be achieved with electron cooling alone.

We need also very good beam scraper system and/or stochastic halo-cleaning system.

3 GeV,68.3 % of anti-protonsIe = 1 Ar0 = 5 mmlC = 30 mB = 0.2 TkT = 1 eVθ = 10-5

radiansβ*

C = 50 mβ*

T = 2.5 mNpbar = 1010

BETACOOL computations

mm 5.0m 5.2m 101.0 6

*T

==××≈

≈−

εβ

turn on transvers

e

heating

turn on pellet ta

rget

(4×101

5 cm-2 )

mm 5.0m 5.2m 101.0 6

*T

==××≈

≈−

εβ

3 GeV,68.3 % of anti-protonsIe = 1 Ar0 = 5 mmlC = 30 mB = 0.2 TkT = 1 eVθ = 10-5

radiansβ*

C = 50 mβ*

T = 2.5 mNpbar = 1010

BETACOOL computations

mm 5.0m 5.2m 101.0 6

*T

==××≈

≈−

εβ

turn on transvers

e

heating

turn on pellet ta

rget

(4×101

5 cm-2 )

β*C chosen so that 92 % of injected beam is always inside of electron beam

mm 5.0m 5.2m 101.0 6

*T

==××≈

≈−

εβ

8 GeV,68.3 % of anti-protonsIe = 1 Ar0 = 5 mmlC = 30 mB = 0.2 TkT = 1 eVθ = 10-5

radiansβ*

C = 100 mβ*

T = 10 mNpbar = 1010

turn on pellet ta

rget

(4×101

5 cm-2 )turn on tra

nsverse

heating

BETACOOL computations

mm 4.0m 10m 1002.0 6

*T

==××≈

≈−

εβ

FNAL RECYCLER 4.3 MeV electron cooling system

Prior Art:

CONGRATULATIONS!!!

The Budker Institute in Novosibirsk (BINP) has performed a detailed study. They propose a 30 m long electron-cooling section with a 0.5 T longitudinal magnetic field with straightness 10-5 radians (rms). They propose to produce the high voltage (up to 8 MV) with an H- cyclotron, which charges the high-voltage terminal.

Prior Art, continued:

We are looking at alternatives, especially to use more conventional means to achieve the high voltage van de Graaff accelerators (“Pelletrons”) as in Fermilab…

drift section is shown too short

H--ion sourceElectron gunElectron collector

Sputter-ion pumps

normal separation box

big separation box

Cdc ccC dynC Corona ring

RFDriver

Beam

Dynode TerminalPressure vessel

Corona ring

2 Acc. Tubes(Dia. 235mm.)

DynodeDiode stack

3.8m.

Diodes

… or (cascade generators, so called (“Dynamitrons”)

Advantages of Pelletron:

• experience at FNAL

• possibilities for copying from FNAL (getting help from FNAL?)

• proven UHV performance

• no need for extensive R&D

Advantages of Dynamitron

• low impedance on electrodes (150 MΩ vs 10 GΩ)

• proven performance with 10-5 voltage stability and ripple

• fast regulation of voltage without corona spikes

• horizontal layout (no need for tower)

We will continue study of both alternatives, but hope to make a choice shortly.

Updated Technical Report must be ready 15 December.

We would very much like to again establish collaboration with BINP, also with JINR, FNAL, BNL...