Nuclotron and Its Control System
V.Andreev, V.Gorchenko, A.Kirichenko, A.Kovalenko, I.Kulikov, V.Mikhailov, V.Monchinsky,S.Romanov, B.Sveshnikov, A.Tsarenkov, B.Vasilishin, M.Voevodin, V.Volkov
Laboratory of High Energies, Joint Institute for Nuclear Research, 141980 Dubna, Russia
Abstract
The status of Nuclotron is presented. The main
parameters and the progress of the Nuclotron Control
System (NCS) are described.
1 Nuclotron status
The first superconducting synchrotron Nuclotron basedon miniature iron-shaped field SC-magnets was put into
operation in March 1993 at the Laboratory of HighEnergies of JINR in Dubna. Eleven runs of the newaccelerator have been performed by the present time. The
investigation of the accelerator systems operation as well
as data taking for physics have been performed. Generallayout of the LHE accelerator facility is presented in Fig.1.

magnetic field correction, vacuum, circulating beamdiagnostics, radio frequency, main power supplies, andradiation safety. The slow extraction and external beamdiagnostics subsystems are still under development.
The basic structure of NCS is shown in Fig.2. The
control system architecture is hierarchical in nature andconsists of two physical levels, an Operator Control Leveland a Front End Level.

Figure 2: Basic structure of NCS.
2.2 Operator control level

Figure 1: General layout of the accelerator facility.
The Nuclotron [1] is intended to accelerate nuclei andmulticharged ions including the heaviest ones (uranium) up
to an energy of 6 Gev/u for the charge to mass ratio Z/A =1/2. There are 96 dipole, 64 quadrupole, 32 correcting
multipole SC-magnets in the Nuclotron magnetic ring witha circumference of 251.5 m. The maximum value of themagnetic field is about 2 T.
2 NCS structure
2.1 General
The Nuclotron Control System project, which is inprogress, started in 1992 and has provided an efficient
support for the machine commissioning through all itsphases.
The Nuclotron Control System [2] in its present form,
together with the Main Control Room and the local
consoles, comprises the following subsystems: cryogenics,
thermometry, magnet diagnostics, an injection beam line,
beam injection, beam diagnostics on the first turns,

The Operator Control Level supplies all the appropriate
man-machine tools for operators to run the accelerator.
High performance workstations, together with generalpurpose server computers, are used at this top level. Theworkstations act as operator consoles, while the servers
provide the communication process, data storage, printing
utilities, a common database, alarm service, a programlibrary, and data exchange between the Nuclotron and theusers.
The NCS is a distributed system, its subsytems aregeographically separated by as much as 500 m. The
common backbone of the system is an Ethernet Local Area
Network (LAN). It runs IPX/SPX and TCP/IP communication protocols and connects console computers to the Front
End Level and physicists’ workstations. As the system hasfour geographically separated parts, LAN is divided into
four independent segments. A SUN Sparc station is used asa LAN bridge to filter communication between the General
JINR Ethernet and Nuclotron network.
The system includes both static and dynamic database.
The static database contains the information necessary todrive all the devices connected to the control system. The
complete information set about the status of the wholemachine is available in the dynamic runtime database. It isupdated each accelerator cycle. The archive database keeps
a long-term history of machine parameters. The status of
all the equipment is recorded into log files once every 30
minutes for further analysis. Access to the databaseinformation is gained by the consoles independently inorder to display relevant parameters about the elements
required by the operators. The library of database accessroutines named the Data Viewer has been developed. These
applications allow users to select data sets for visualobservation or color graphic printing on remote
workstations. Multiple Data Viewers can be activatedsimultaneously.
The alarm server monitors continuously any changes ofthe state of predefined equipments and detects faultconditions; anomalies are displayed on an alarm screen andduplicated by multimedia audio devices for the operator totake an appropriate action. Alarm messages are archived
for retrieval and off-line inspection.
An information management subsystem was designed
and is now under implementation to interchange information between the NCS and the Nuclotron users (Fig.3).

Figure 3: The simplified data exchange diagram.
The element tables in the dynamic database areduplicated at the data exchange server in order to beavailable to the physicists. This information can be bothobserved on display screens, and processed and written on
disks together with experimental data for future off-line
physics analysis. Some data are broadcast via cable TV
channels. The same subsystem also sends experimental
information, such as background levels and detector
counting rates to the NCS. The Nuclotron operators use
this information to adjust the machine.

rule, are diskless systems, and they can be installed inharsh environments. The controller developed by our own
staff is based on an OCTAGON micro-PC. An onboard
Ethernet interface allows software downloading and remotedevice control. The main part of the existing hardwareinterface is in the CAMAC standard. All CAMAC modulesof the total number up to 600 were developed andmanufactured at the LHE, JINR. However, we are planningto implement more extensively acquisi-tion and control
boards in the industrial PC standard.
3 Subsystems
3.1 Cryogenics & thermometry
The parameters under control are the quality of a twophase flow (the mass vapour content of helium in thesupply headers), the density and flow rate of two-phase
cryoproduct flows. The principle of measurement is basedon the dependence of the resonance frequency of an
oscillating RF-resonator with a high Q-factor on thedielectric permeability of the controlled flow [3]. At thesame time, the subsystem provides a helium pressure
measurement in direct and back flows, the helium andnitrogen levels and pressure in the separators and storage
tanks, as well.
The temperature measurement is one of the central
points in the cryogenic subsystem. This makes it possible
to monitor and control cool-down and warm-up of theaccelerator magnets, to support operational conditions
during machine runs, to indicate the deviations of coolingparameters from nominal ones, and to carry out
temperature diagnostics of the cryogenic components
during accidents (quenches, vacuum breakdowns, etc.).
The subsystem provides the temperature measurements of
the Nuclotron elements at more than 600 control points.
The measurement range is from 4 to 300 K with theresolution of 25 mK at temperatures of ~4 K. Fig.4
illustrates one set of the data presented by the subsystem.

2.3 Front end level
The Front End Level deals with real-time controls. At
present, the total number of points for measurement andcontrol are about 3000. This number will be increased byabout 20% when the beam slow extraction subsystem iscompleted. The expected average rate of real-time
acquisition is 90 kByte/s.
This level comprises both industrial rack-mountable PCsfrom ADVANTECH, equipped with I/O boards and dataacquisition modules, and intelligent CAMAC cratecontrollers with embedded micro-PCs. These ones, as aFigure 4: The temperature distribution along the Nuclotron
ring in a process of cool-down.
3.2 Beam injection
The subsystem has been set up to control and monitor
the equipment on a beam transport line, power supplies, asuperconducting inflector magnet, inflector plates, beam

instrumentation elements in the ring, timing and synchronization.
In order to observe the beam behavior during injection
and at the initial stage of beam circulation, various
monitoring devices were made for the subsystem. The
diagnostics of the beam injection transport line include
2 wire collector profilometers, 1 wire collector beam
current monitor, 2 destructive screen monitors, and 2
Faraday cups. The beam profile monitor consists of X- andY-wire planes. Each plane has 32 golden tungsten wires 0.1
mm in diameter separated by 2 mm. The beam current
monitor has one plane with wires connected in parallel.
Image processing technique based on fluorescent screens,
CCD cameras, and frame-grabbers ensures the following
possibilities: fluorescent screen selection and setting inside
the beam, video tuning, background subtraction, pseudocolor for displays, the ability to save and restore specificimages, snapshot and live mode selection.
The accelerator ring diagnostics are composed of 5 wirecollector profilometers, 21 electrostatic beam positionmonitors (BPMs), 1 electrostatic intensity pick-up,
1 magnetic pick-up, 4 destructive screen monitors,
4 Faraday cups. Two of five profilometers are placed at theentrance and the exit of the inflector magnet. We areplanning to measure emittance using the profilometers at
the end of the transport line, at the inflector magnet
entrance, and in the first straight section of the ring. It willallow us to adjust more exactly injected beam matching to
the ring lattice. Using the position and intensity pick-ups
with fast (10-50 MHz) buffered ADCs of 8-bit resolutions,beam information for each revolution can be acquired. It ispossible to obtain transverse and longitudinal information
for 800 first turns in parallel with orbit acquisition. Fig.5
shows incorrected closed R- and Z- orbits measured at thefield of injection.

used to keep the required ratio IQD/IQF during theaccelerator cycle.
The BM magnetic field shape is set by a pulse function
generator which produces a reference burst (Bo-train) witha 0.1 Gs resolution. This train increments a pattern analog
function generator based on a 16-bit DAC. A real B-train
off the reference bending magnet and the corresponding
analog function are used for feedback loop. The current
magnetic field of the BMs is used as reference function for
the focusing and defocusing magnets, i.e. the BM power
supply is a master and the QF and QD supplies are slave
ones. The QF and QD trains are utilized for control as
described above. Fig.6 shows the magnetic field cycle
parameters.

Figure 6: Example of magnetic field cycle parameters.
4 Conclusion
At present, though not at its final dimension, the control
system is fully operational and has the proposed
functionality. An essential step to provide the accelerator
with a high performance and flexible computer control
environment has been accomplished. Up to now, 28
computers and 35 CAMAC chassis are installed in thecontrol system.
Acknowledgments
We would like to thank our colleagues who havecontributed to the NCS project. The authors are grateful toL.Sveshnikova for her help in preparing this paper.
References

Figure 5: Closed R-and Z- orbits.
3.3 Main magnetic field control
The dedicated control subsystem for pulsed power
supplies of the magnets was designed, allowing thereproduction of the desired B and Q fields to better than
5·10-4 at injection.
The bending (BM), focusing (QF) and defocusing (QD)
magnets are powered by three supplies. The BMs aredriven by supply of a 6.3 kA nominal current. The QFs andQDs are connected in series and powered by supply of 6kA. Besides, an additional supply of 200 A for the QFs is[1] A.D.Kovalenko, "Status of the Nuclotron", Proc. of
the Fourth European Particle Accelerator Conference(EPAC 94).
[2] V.Andreev et al. "Nuclotron Control System", Proc. of
the 1997 Particle Accelerator Conference (PAC 97)[3] A.I.Alexeev et al, "Application of Radio Frequency
Method to Measurements in Cryogenics", Cryogenics,
1991, Vol.31, pp.1020-1029.