ATF Status December/2002H. HayanoH. Hayano

Multibunch photo-cathode RF-gunMultibunch emittance

Instrumentation developmentsPlans for spring 2003 run

ISG9 at KEK 12/10/2002

ATF Introduction

E=1.28GeVNe=1x1010 e-/bunch 1 ~ 20 bunchesRep=1.5HzX emit=2.5E-6( at 0 intensity)

Y emit=2.5E-8( at 0 intensity)

Single Bunch emittance

x = 2.0x10-9 ( xn = 5.0x10-6)

y = 2.1x10-11(yn = 5.3x10-8) at 9x109 intensity

Multibunch photo-cathode RF gun

For better MB injection into DR generation of high quality multibunch

low emittance, low energy spread, high & flat intensity Combination of BNL-cavity and Cs2Te cathode enough operation experience in CTF & TTF New laser system; 20 bunch, 2.8ns spacing, 266nm Nd:YVO4 (1064nm) 357MHz mode-lock laser + amplifier Load-lock system for Cs2Te cathode block extra cathode blocks and evaporation chamber KEK built gun-cavity precise machining and blazing by KEK machine center

RF-gun cavity & cathode block

Multibunch photo-cathode RF-gun

IP 400 l/s

3m Acc. structureRF gun cavitySolenoid

transport movers

Multibunch photo-cathode RF gun assemblyJune ~ Oct. 2002

Multibunch Laser

IP 400 l/s

ION source for cleaning

Evaporation chamber

Cathode loading axisGV

GVGV GV

Gun cavity, Load-lock & Laser system

RF gun beam at 80MeV Beam Intensity ~1x1010/bunch Normalized Emittance y= 28x10-6 rad.m Bunch length z= 6.4 ~ 7.9 ps Energy spread dE/E = 4.9% full-width Q.E. of CsTe cathode 16% initial, 2~3% with RF ON

& constant over a week

multibunch beam in DR

3 bunch

19 bunchWall current monitor

Beam intensity

Multibunch emittance Beam intensity in DR 0.3~ 0.5 x1010 e-, 19 bunch, 2.8ns spacing with 0.78Hz repetition limited by max. beam power of radiation safety Monitors of MB emittance MB (or projected) Laser-wire Projected SR interference monitor, X-ray SR monitor MB (or projected) wire scanner: (EXT-line coupling problem) Problem of MB emittance big energy fluctuation ( coupled bunch longitudinal oscillation )

New Laser wire : X & Y scan

X profile

Y profile

Two wire chamber

Emittance by Laser wire

1% y/x emittance ratio

X-ray SR profilesX profile Y profile

39.27 +/- 0.53 [μm] 7.30 +/- 0.12 [μm]

xXSR = 1.8 x10-9 , y

XSR = 1.1 x10-11 ( ~ 3 x109 bunch intensity)

After subtracting dispersion effect

MB energy fluctuation

MB longitudinal oscillation

Candidates of impedance source DR cavity HOM no response for temp., tuner, Vc, feedback, direct RF feedback, no enhanced signal from HOM pickup Kicker ceramic insulation temp. rise with beam, HFSS calculation suggestion Other source? tune exciter electrode?

New instrumentation developments ODR beam size monitor observation of Diffraction Radiation in visible light new slit target was installed. New clip-circuit for DR BPM single shot 3µm resolution circuit Beam tilt detection by cavity-BPM study was started (SLAC) nm resolution cavity-BPM 3 cavity BPM setup was started Multibunch BPM circuit test continuing (SLAC) circuit under fabrication (KEK)

end

Plans for Autumn-Spring 2003 run Run by multibunch photo-cathode RF gun smooth multibunch operation from 1 bunch to 20 bunches with high intensity and low beam loss MB emittance study emittance was confirmed by Laser Wire. Longitudinal oscillation was observed. need to fix them by identifying the source. DR re-alignment & Beam Based Alignment using new coming BPM circuit (Jan. 2003), more precise orbit control will be possible. EXT line coupling study search of coupling source (EXT kicker?) Instrumentation developments LW, XSR monitor, ODR monitor, cavity-BPM, multibunch BPM, etc