status and prospects of the tau-charm factory in novosibirske.levichev superct project (rupac-2010)...

Status and Prospects of the Tau-Charm Factory in Novosibirsk

E.Levichev

Budker Institute of Nuclear PhysicsNovosibirsk, Russia

XXII Russian Particle Accelerator Conference RuPAC-2010September 27 – October 1 2010, Protvino, Moscow Region, Russia

E.Levichev SuperCT Project (RuPAC-2010)

Outline

BINP colliders

Crab waist approach

Scientific case and SCT factory specs

SCT factory description

Status and plans

Conclusion


BINP Colliders

VEPP-2000 E = 1 GeVRound beamsIn operation 2009 - …

RuPAC’10 D.Shwartz

VEPP-4M E = 1 - 5 GeVEnergy calibration 10-6

In operation 2000 – 2013 (?)

RuPAC’10 S.Nikitin


Crab Waist collision

A new idea of Crab Waist collision firstly proposed by Pantaleo Raimondi (LNF/INFN, Frascati, Italy) allows luminosity increase by factor 100 (!)without increase of beam intensity or decrease of bunch length.

The idea was proven theoretically and by computer simulation by P.Raimondi, M.Zobov (LNF, Italy) and D.Shatilov (BINP, Novosibirsk)

1. P.Raimondi, 2° SuperB Workshop,

March 2006

2. P.Raimondi, D.Shatilov, M.Zobov,

physics/0702033

Raimondi

Shatilov and Zobov

RuPAC’10 M.Zobov


Scientific case

► D-Dbar mixing

► CP violation searches in charm decays

► Rare and forbidden charm decays

► Standard Model tests in leptons decays

► Searches for lepton flavor violation →mg

► CP/T violation searches in leptons decays

Requirements: E = 1.5 -2.5 GeV/beam, L > 1034 cm-2 s-1,

longitudinal polarization

► Production of the polarized anti-nucleons

Energy = 1 GeV with reduced luminosity


Specifications

Beam Energy from 1.0 to 2.5 GeV

Luminosity ~ 1035 at 2 GeV

Longitudinal Polarization of Electrons at IP

No Energy Asymmetry

No Energy Monochromatization

Energy Calibration with Medium Accuracy is Sufficient (Compton Backscattering)


Key features

Two Rings

Crab waist collisions

Small Beta Function at IP (βy ~ 800 um)

Superconducting wigglers to keep the same damping and emittance in the whole energy range

High Beam Current

5 Siberian Snakes

Electron Polarization Source

2.5 GeV Linac

50 Hz Injection Rate


Super Tau Charm factory layout


Main ring


Energy 1.0 GeV 1.5 GeV 2.0 GeV 2.5 GeV

Circumference 766.6 m

Emittance hor/ver 8 nm/0.04 nm @ 0.5% coupling

Damping time hor/ver/long 30/30/15 ms

Bunch length 16 mm 11 mm 10 mm 10 mm

Energy spread 10.1·10-4 9.96·10-4 8.44·10-4 7.38·10-4

Momentum compaction 1.00·10-3 1.06·10-3 1.06·10-3 1.06·10-3

Synchrotron tune 0.007 0.010 0.009 0.008

RF frequency 508 MHz

Harmonic number 1300

Particles in bunch 7·1010

Number of bunches 390 (10% gap)

Bunch current 4.4 mA

Total beam current 1.7 A

Beam-beam parameter 0.15 0.15 0.12 0.095

Luminosity 0.63·1035 0.95·1035 1.00·1035 1.00·1035

Main parameters


Optical functions


Interaction region optics

IP

FF

telescope

Y Section

of chroms

correction

X Section

of chroms

correction

Crab

SextEnd of

the telescope

L1/2 = 75 m


Final focus system

QD0

Detector Yoke

QF1

Anti Sold

e-

e+

Cryostat


QD0 Lens

SC iron yoke twin aperture magnet

Excitation current 1.15 kA

Aperture diam 2 cm

Gradient 10.7 kGs/cm

Length 20 cm

Prototype of QD0 now is constructed at BINP


Control of radiation parameters

Energy 1.0 1.5 2.0 2.5 GeV

Horizontal Emittance 8 nm·rad

Damping time 30 msec

Energy spread 1.01 0.99 0.85 0.74 ·10-3

Wiggler field 45 33 22 0 kGs

Energy loss 170 256 343 434 keV

SR Power @ Bends 19 96 304 743 kW

SR Power @ Wiggs 272 342 282 0 kW

Total SR Power 291 438 586 743 kW

4x1.5m Wigglers @ 50 kGs λ=20cm

Ibeam = 1.7 A


The damping wigglers keep the damping time τx =30 ms and the horizontal emittance (8 nm) in the energy range 1.0 – 2.5 GeV

Wiggler with similar parameters produced by BINP

Damping wigglers


Betatron tunes scan for Beam-Beam


Beam-Beam simulation

Simulation by D. Shatilov


Polarization scheme

Polarization scheme with 5 snakes (arc=720 , 4 damping wigglers in the arc’s middle )


1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.60

0.2

0.4

0.6

0.8

1

Beam Energy, GeV

Pola

riza

tion

Deg

ree

5 snakes

1 snake

3 snakes

Polarization scheme


Energy calibrationCompton backscattering Ecalibration (~10-410-5)

Spectrum edge

Na24 (1)=1368.625 keV

Na24 (2)=2754.008 keV

Na24 (1+2)=4122.633 keV

5105 E

E


2 GeV Linac

Positron injector


Nominal Parameters Production: N=2·1010 e+/sec Extraction Rate: 50 Hz

Upgrade

New Electron Gun N=2·1010 e- 6·1010 e- (×3 times)

New Optics for Positron Target (×1.5 times)

Monochromatization of Positron Energy Spread (×2 times)

Electron Beam Energy 300 MeV 450 МэВ (×1.5 times)

Extraction Rate 50 Hz (w/o accumulate)

2 Bunches in Damping Ring

Total: N = 2·1011 e+/sec

Positron injector


Electron polarization source

Beam polarization 60–80% (90%) Cathode voltage 100 kV Photocathode type Strained InGaAsP Laser type Ti–Sapphire Light wavelength 700–850 nm Laser power in a pulse 200 W Pulse duration 2.1 ms Repetition rate 1 Hz (50 Hz) Max. current from a gun 150 mA Operational current 15–20 mA Photocathode lifetime 190–560 hours

Polarized electron source produced by BINP for AmPS


Status and nearest plans

Draft version of CDR has completed

As it was agreed with KEK two factories will

establish a single international project with

similar approaches and complementary

physics

ECFA will consider STCF project in

November

CERN supporting procedure in discussion

Documents for the project application to

Russian Government are under preparation


Summary

Crab waist approach is a novel exciting and

promising idea for substantial luminosity increase

Realistic project of Super Tau Charm Factory is

developed (No major limitations)

A CDR is completed

Prototype of the FF key element QD0 lens is being

constructed in BINP