CAS 2005
TRIESTE
APPLICATION OF THE BEAM PROFILE MONITOR FOR VEPP-4M TUNING
Andrey Zhuravlev
Technical parameters
The BEAM profile monitor data:
The beam kick and beam-beam effects
Budker Institute of Nuclear Physics
Beam dipole oscillations (black plot) and size Y behavior (red plot) after
kick, Ie- =5.4 mA. It is the limit current for the VEPP-4M. The beam losses
after a small kick and quadrupole mode instability take place.
Multi-anode PMT R5900U-00-L16 HAMAMATSU
Amplitude of the signal is scaled in artificial colors.
MAPMT has 16 anode strips. The size of the single anode is 0.816 mm.
The MAPMT Technical Parameters
The Vepp-4 Facility Technical Parameters
VEPP-3 circumference
75 м
VEPP-4M circumference
366 м
VEPP-3 maximum energy
2000 МэВ
VEPP-3 Maximum current
200 мА
VEPP-4M maximum energy
6000 МэВ
VEPP-4M Maximum electron/positron currents
80 мА
0,2 х 0,6
VEPP-4M beam size
Size
250 x 100 x 100 mm
Interface
100М ethernet
Internal memory
~4 М (217 beam profiles at
16 points)
Discontinuity of record
1… 28 turns
Beam dipole oscillations (black plot) and size Y behavior (red plot) after
kick, Ie- = 220 A.
мм2
Collider luminosity
1.5*10 32
VEPP-3 period of revolution
0,25 мс
VEPP-4M period of revolution
1,22 мс
Example of the single beam profile
fitted by the Gauss function.
Analyzable frequency
range
10 Hz … 1 MHz
Single anode size
0.8  16 mm
x 64
The beam dipole oscillations (black plot) and Y behavior (red plot) during
the beams convergence in the interaction point. Duration of the single
turn is 1220 ns. Channel constant is 0.12 mm. Ie+= 3.4 mA, Ie- = 3.0 mA.
Arrangement and principle of operation
The lens. Optical magnification
within limits of 320.
To ADC
MAPMT
Phase oscillations of the beam are shown.
Beam image,
created by the
primary optical
system
 64
The convergence of the beams with currents of
accompanied by quadrupole instability.
16 anode strips
Iе+=2.4
mA,
Iе-
=2.9 mA,
The BEAM profile monitor data: the Beam frequencies measurement
E=1777 MeV
frequency
Evolution of the betatron frequencies during scanning
The Fourie-spectrum of the betatron fluctuations
sy
100
sign/noise
Start pulse
E=1850 MeV
0.011
ADC triggering
80
60
40
20
0.01
The typical MAPMT signal and the operating point
for the amplitude measurement
Qy
120
0.012
Urf [kV]
0.009
250
Qx
Qx
смена
12. 05. 05. 12.05.
TheНочная
VEPP-4M
night run.
Qs
s
0.013
The operating cycle of the device is as follows. MAPMT signals are recorded to
the ADC after start pulse. The starting moment is either chosen by user or
coincides with the beams convergence in the interaction point, “kick”, beam
pass by, etc. The ADC triggering is synchronized with the beam revolution
frequency. The recorded signals are stored in the internal memory and read
out to the PC.
Qy
Time
The measured low frequency oscillations of the beam (upper plot).
The measured synchrotron s and betatron X, Y frequency of the
beam (down plot).
0.014
amplitude
frequency
Layout of the optical diagnostic system.
A visible part of the SR is reflected from the cooled
metallic mirror and leaves the VEPP-4M vacuum
Chamber through a glass window
Optical layout of the diagnostics. The lens sets up a beam image on the
photocathode of the MAPMT. The radial profile measurement is shown.
300
350
400
450
500
550
600
The dependence of the synchrotron frequency
s with respect to the accelerating voltage Urf
0
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
sx
Time
Monitoring of parasitic phase oscillations.
MAPMT data are shown.
Vertical beam size depending on
betatron frequencies