PHYSICAL PROJECT OF BOOSTER

FOR NICA ACCELERATOR COMPLEX

Alexey Tuzikov, Nikolay Agapov, Andrey Butenko, Alexey Eliseev, Viktor Karpinsky, Hamlet Khodzhibagiyan,

Alexander Kovalenko, Grigory Kuznetsov, Igor Meshkov, Vladimir Mikhaylov, Valery Monchinsky, Anatoly Sidorin,

Alexander Smirnov, Grigoriy Trubnikov, Bogdan Vasilishin

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Introduction

Booster is a standard element in the schemes of the synchrotron facilities of heavy ions. In our case its objectives are as follows.

1. Acceleration of the beams to an energy sufficient for the complete stripping of the ions Au32+.

2. The accumulation of Au32+ ions in different modes of ion source operation.

3. The relief of requirements for vacuum system in Nuclotron. 4. The increase of ion phase density in the Booster using electron

cooling at the optimum energies close to 100 MeV / nucleon. 5. The refusal of the acceleration in collider.

It should be noted that Nuclotron designed as an accelerator for nuclei up to calcium therefore these features can only be implemented in a synchrotron built for heavy ions like Au32+.

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Position

The iron yoke of the Synchrophasotron after the magnet winding is removed, gives a free tunnel of 4 x 2.3 m2. The present layout of the Nuclotron and existing injection and extraction systems make it possible to place the Booster having 211.2 m circumference and four fold symmetry inside the Synchrophasotron yoke.

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Position

Synchrophasotron yoke

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Main parametersFold symmetry 4

Quadrupole periodicity 24

Injection/extraction energy Au32+ 6.2/600 MeV/u

Magnetic rigidity 2.2 25.0 T·m

Dipole field 0.16 1.8 T

Pulse repetition rate 0.25 Hz

Magnetic field ramp 1 T/s

Intensity limit 2.5∙109 particle per pulse

Au79+ beam intensity (after stripping) 1.5×109

Vacuum 10-11 Torr

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Main parametersCycle diagram

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LatticeFODO lattice

Dipoles

Number of dipoles 40

Maximum magnetic field, T 1.8

Effective field length, m 2.2

Bending angle, deg 9.0

Curvature radius , m 14.09

Booster superperiod lattice

Quadrupoles

Number of quadrupoles 48

Field gradient, T/m 19.7/-20.3

Effective field length, m 0.4

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LatticeFODO lattice

Booster superperiod lattice functions Working diagram

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Superconducting magnets

Dipole magnet in cryostat Hollow superconducting cable

1 - copper-nickel tube, 2 - NbTi strands, 3 - strands binding by wire, 4 - kapton tape, 5 - glassfiber tape

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InjectionThe injection scheme supposes few modes of ion accumulation depending on operation mode of ion sources:

One turn injection Four (three) turn injection Twice (triple) repeated one turn injection Multi turn injection with coupling resonance and electron cooling

BIP1BIP2 BIP3

BIP4

BIES

-200-150-100-50

050

100150200250300350

-0.5 4.5 9.5 14.5 19.5 24.5

s, m

x, m

m

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InjectionFour turn injection

X

X΄

septum

X

X΄ ste

bumpX

Booster acceptance

septum

X

X΄

st

Booster acceptance

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Acceleration

№ Parameter

1. RF range 0.5 – 2.4 MHz

2. Harmonic 4/1

3. Cavity count 2

4. Minimum voltage amplitude at adiabatic capture 100 V

5. Voltage amplitude at acceleration 10 kV

The Booster RF cycle is composed of four parts: the adiabatic trapping at fixed frequency (flat bottom), the beam acceleration at the forth harmonics of the revolution

frequency up to 100 MeV/u and debunching, the beam bunching at the first harmonics of the revolution

frequency together with the electron cooling, the beam acceleration at the first harmonics of the revolution

frequency up to 600 MeV/u.

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Acceleration

II IV

Еk/u(MeV)

Time

III

0.48 s ~ 1.0 s 0.98 s

I

6.2

100

600

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Electron cooling

The Booster electron cooling system is aimed to form required optimal phase volume of the bunch for their further acceleration in Nuclotron. The maximum designed electron energy is 60 keV.

Numerical simulations of the cooling process showed that the cooling section of 4 m of the total length and electron current of 1 A provides required ion beam parameters at the ion energy of 100 MeV/u. The parameters are typical for conventional electron cooling systems, the energy corresponds to minimum range of the RF frequency variation (0.6 2.4 MHz) during the Booster working cycle. To adjust the cooling section with the SC magnetic system at minimum length, one plan to use a superconducting solenoid for the electron beam transportation, that is main technical peculiarity of the Booster cooler.

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Electron cooling

Electron cooler: working design

Electron gunElectron collector

General view of the electron cooler

1945

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Extraction Fast extraction system consists of

kicker magnet and superconducting Lambertson Magnet (steel septum).

Slow extraction includes 4 quadrupole and 4 sextupole lenses, electrostatic septum and septum magnet. Minimum emittance of extracted beam will be provided by Hardt condition and dynamic bump.

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