MACHINE OPERATIONS AND STATISTICS ON THE VEPP-4 COMPLEX
A. Bogomyagkov, D. Filimonov, S. Karnaev∗ , E. Kremyanskaya, S. Mishnev,
I. Nikolaev, E. Simonov, S. Smirnov, D. Shatilov, A.Veklov, V. Zorin,
Budker Institute of Nuclear Physics, Novosibirsk
Abstract
The VEPP-4 complex provides electron and positron
beams for different experiments in parallel.
Due to implementation Linux-based machines in theVEPP-4 Control System the vast statistics are available
and are used for the analysis of the stability and reliabilityof the machines. The improvement of the Control Systemallowed us to successfully accomplish the precise
experiment of measuring of the J/psi- and psi'-mesonmasses. Now the experiment of tau-lepton massmeasurement is being prepared on the VEPP-4 complex
in which the analysis of the machine parameters will playa vital part.

The paper reviews an opportunity for data acquisitionin the VEPP-4 Control System. Machine operations
schedules for different user works are also presented inthis paper.

1 INTRODUCTION
The VEPP-4 complex [1] is intended for providing
experiments with colliding electron-positron beams,experiments on nuclear physics, experiments withsynchrotron radiation.
The VEPP-4 accelerator facility consists of VEPP-4M
collider with 365 m circumference (1 - 6 GeV), 2 GeV
multi-purpose VEPP-3 storage ring and 350 MeV pulse
electron/positron injector. There is pulse transfer linefrom VEPP-3 to VEPP-4M (see Fig.1).

Figure 1: Layout of the VEPP-4 facility.
Both rings, VEPP-3 and VEPP-4, are used forproviding experiments. In spite of the fact that VEPP-3 isthe booster for VEPP-4, there is a possibility to performdifferent experiments on VEPP-3 and VEPP-4
simultaneously.
The VEPP-4 Control System [2] was designed morethan fifteen years ago and based on the home-developed∗

karnaev@inp.nsk.su

CAMAC-embedded minicomputers Odrenok. Currently
the VEPP-4 Control System includes 14 Odrenok
computers. Each Odrenok is responsible for the control ofindividual parts of the VEPP-4 complex or for the part ofdiagnostics (vacuum and temperature, beam diagnostics,etc).

Five years ago, all Odrenok computers were connected
via Ethernet network. This step allowed us to force anintegration of PCs into the VEPP-4 control system.
PCs in the Control System have allowed us to develop
data accumulation system for following data analysis.
This system provides data acquisition from Odrenok
computers: set currents in magnetic elements of theVEPP-4M collider and measured values of the currents,
temperature of all the devices on the VEPP-4 facility,vacuum, etc.
The data acquisition system allowed us to carefully
control the energy of particles in the VEPP-4M collider
during J/Ψ and Ψ'-mesons mass measurement
experiments during the 2001/2002 season [3].

2 VEPP-3 OPERATIONS
2.1 Booster operations
Pulse injector (1 Hz) of VEPP-3 is intended for
production of electron and positron beams with particles
energy 350 MeV. Injector consists of 50 MeV linac and350 MeV synchrotron. Linac is RF powered by pulse
GIROCON 430 MHz generator.
Positrons are produced after linac from electron beamon tungsten target 3 mm thickness. Number of particles inelectron bunch extracted from synchrotron is 1010,
number of particles in positron bunch is 2×108.
Booster operations are (see Fig. 2):(a) at first the positrons are accumulated during 20
minutes in VEPP-3,(b) then the positron beam is accelerated andtransferred to VEPP-4M.

(c) the polarities of magnetic systems of VEPP-3 andthe injector are changed, and within 10 minutes theelectron beam is accumulated and accelerated,(d) after transferring of electron beam the positrons
are accumulated again.
The specified current of positron beam is hold in
VEPP-3 (e), while the experiments with beams in
VEPP-4M are performed. In the case of 2×2 bunches in
VEPP-4M the operations (a), (b) (see Fig. 2)are madetwice.

2.2 Physical experiments providing
In addition to use as the booster for VEPP-4M collider
VEPP-3 storage ring is used for experiments withsynchrotron radiation and for experiments with polarizedgas internal target. Both types of experiments can be
conducted simultaneously. There is an electron beam in
VEPP-3 in this case. Synchrotron radiation is produced inthree-pole wiggler with energy range from up to 40 keV.
The following operations are executed in this case:(a) on injection energy (350 MeV) the desirable
current is accumulated in one bunch during 2-5minutes,(b) the accumulated bunch is accelerated up to energy
2 GeV,(c) the wiggler for generation of the synchrotron
radiation is turned on,(d) the experiment lasts from 1 till 4-5 hours
depending on desire of the users.
During the experiment the orbit stabilization using theposition of the spot of the synchrotron radiation bunch iscarried out.
(e) after the finish of the experiment the magnetic
cycle of the iron of magnetic elements is executedfor setting the injection mode of the storage ring.

Ivepp3 (mA)

Ivepp4 (mA)
b)

20c)

e)g)h)d)

4a)

102i)

f)

j)

0.5

1

2.5

Figure 2: Booster operations of the VEPP-4 facility.

3t (h)

3 VEPP-4M OPERATIONS
4.1 High energy physics experiments providing
VEPP-4M e+e– collider [1] was intended for themaximum energy up to 6 GeV to study physics ofϒ -meson and two-photon processes [4]. The collider
worked in this mode in the first half of the 1980's.
Recently the facility efforts are concentrated in J/ψ and τ
lepton physics in the low energy range of E=1.5–1.8 GeV[5].
During one experimental cycle the following operations
are performed on the VEPP-4M facility (Fig. 2):f) the injection of the new positron beam fromVEPP-3,g) injection of the new electron beam,h) acceleration (or deceleration) of injected beams,i) experiment time,j) magnetic cycle time.
During regular J/Ψ meson or τ lepton study the collider
energy is calibrated with an accuracy of 10-4 or betterusing the method of resonance depolarization [6].
The diagram of the operations in the case of thestatistics gathering is shown in Fig.6.

have to be applied. For instance, a long-term relative
stability of the dipole magnetic field should be better than
5×10-6. Besides, magnetic field imperfections can destroy
beam polarization with the characteristic time τr.
Estimation shows that the spin decay time for VEPP-4M
is around τr ~ 30 min for the τ lepton threshold energy inthe case of vertical close orbit distortion rms value ~ 100µm. Since depolarization rate depends strongly on thespin resonance tune, magnetic imperfections and magnets
misalignment can significantly limit the energy
calibration time. These facts make us pay serious
attention to the different aspects of the machine stability(power supplies, temperature, geodetic alignment, etc.).

4.2Data acquisition
Almost all measuring electronics in the VEPP-4
Control System is connected to Odrenok computers [2].
Therefore special software was designed to transfer datafrom Odrenoks to PCs (see Fig.3).
ODRENOK-1#BANK1

4.2 Nuclear physics and SR experiments
providing
There is ROKK-1M installation (see Fig.1) on theVEPP-4 facility which is intended for production ofbunches of back-scattered compton γ quanta.
There are several beam lines for extraction ofsynchrotron radiation beams in the middle of north halfring. Synchrotron radiation is produced in the bending
magnets.
The following operations are performed for providing
nuclear experiments and experiments with synchrotron
radiation:(a) injection and accelerating of one or several (up tofour) electron beams from VEPP-3,(b) experimental time from 1 up to 5 hours,(c) when the beam current in VEPP-4M decreases
down to specific level, VEPP-3 injector is turnedon and a new beam is accumulated in VEPP-3,(d) when VEPP-3 is ready to accelerate the new beam
VEPP-4 start the magnetic cycle for setting theinjection mode. VEPP-3 accelerates the beam inparallel.

4 STATISTICS HANDLING
4.1 Urgency of the problem
For carrying out an experiment on a precision
measurement of the tau-lepton mass near its production
threshold of 1.8 GeV it is necessary to know the exact
energy of colliding particles.
To calibrate the beam energy with high accuracy, rather
hard requirements for stability of VEPP-4M parameters

Measuringprogram 1

Measuring electronics
ODRENOK-2

Measuring
program 2

PC-2
Kadrserver#BANK2

Application 2

Measuring
program 3

Measuring electronics
PC-1
PC-3

HD

Application 1

Application 3
Application 4

Figure 3: Data acquisition scheme.
In Odrenok all required data is read automatically by
the special resident measuring programs. The interaction
with electronics in each Odrenok is made via the singularprogram, usually named #BANK. The measuring
programs send data to the special server in PC named
kadrserver via Ethernet. Home-developed low-leveltransfer protocol requires that the data size in one datatransfer does not exceed the size of Ethernet package (1.5kbytes).
Kadrserver runs as the daemon process and is
automatically started at rebooting of Linux. Kadrserver
receives packages from Odrenoks and puts data tospecified files in a specified directory on the hard disk of
the PC. This directory mounted to all PCs of the Control

System, so applications running in PCs can read datafrom the files.
Data in each file is refreshed when kadrserver receives
the packets from Odrenoks. So applications in PCs mustsave necessary data in their own files for long-term
statistics.

4.3Data storing and analysis
All VEPP-4 Control System data require about 10
kbytes memory per second for saving. Therefore thespecial programs were developed to record selected data
for long-time storage.
Data from Odrenok measuring programs comes as
fixed-length blocks with fixed contents. Kadrserver
handles these blocks and writes data to text files. For
reading required parameter, application must know thefile name and a data position in the file (number of lineand position into the line).
The universal data filter kadrclient provides easy
manipulations with different groups of observed values.
Kadrclient can read one or several data files produced bykadrserver and write specified data to a specified text file
as a new line. At the beginning of each line written bykadrclient date and time of recording is placed. Files
made by kadrclient are conveniently displayed using
interactive plotting program gnuplot [7]. Gnuplot
commands required for different cases are included in the
text files, which are loaded via the "load" gnupot
command. Special scripts provide the observation of thediagrams in real time.

During the experiment of J/Ψ or Ψ'-mesons massmeasurement, it was very important to observe main
parameters of collider VEPP-4M.
For observation of the stored parameters theapplications based on the ROOT-package [8] weredeveloped.
The special application named monit provides for aperiodical saving of the data processed by kadrserver.
Monit converts all specified data from different text files
to a single file in ROOT-format during 24 hours. The
name of this file includes date of saving.
Another application named status provides a graphicvisualization of these files. The screen of this program isshown in Fig. 4. Status provides an easy choice of
desirable parameters and graphic output flexibility(stretching/shrinking of horizontal and vertical scales).
For more detailed long-time analysis, a special script
was developed to save all significant VEPP-4M
parameters to PostgreSQL tables. The period of saving is
10 minutes.
Many parameters of the facility are picked in the block
STAP (Status Page) in the Odrenok’s fileserver whichruns under Linux in PC. Each program running in
Odrenok can write data into this block. The file server
sends STAP block every second as the single broadcast
datagram via Ethernet connecting all VEPP-4 Control
System computers. There is stapserver program which
receives package STAP and writes data to specified filefor the other applications. Some main parameters areshown in [9].

5 REFERENCES[1] V.Anashin at al, in Proc. of the EPAC’98 (Stockholm,1998) vol.1, p.400.
[2] A.Aleshaev et al, “VEPP-4 Control System”,
ICALEPCS'95, Chicago, USA, p.799, F-PO-2.
[3] http://accelconf.web.cern.ch/AccelConf/e02/papers/M
OPRI016.pdf[4] S.A.Nikitin, in Proc.of Intern. Workshop e+eFactories`99, KEK, Japan, 1999, p.37.
[5] E.Levichev, in Proc., HEACC-2000, Tsukuba, Japan,
2000, p.
[6] Ya.S.Derbenev et al, Part. Acc., v.8 (1978).
[7] http://www.ucc.ie/gnuplot/gnuplot.html[8] http://root.cern.ch/root/Welcome.html[9] v4.inp.nsk.su/~vepp4/status/Vepp4Status1.html

Figure 4: The screen of the VEPP-4M parameters
observation program.