Development of the Nuclotron Accelerator Complex for generation heavy ion beams with an energy of 5 GeV/u (project “Nuclotron-M” – 1 st stage of the NICA/MPD facility) A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

Authors: JINR: N.Agapov, V. Alexandrov, A.Alfeev, V.Andreev, A.Bazanov, V.Bartenev, V.Batin, N.Blinov, O.Brovko, A.Butenko, A.Govorov, A.Gromov, E.D.Donets, E.E.Donets, D.E.Donets, A.Donyagin, V.Drobin, A.Eliseev, V.Ershov, V.Fimushkin, E.Ivanov, I.Issinsky, V.Karpinsky, Yu.Karachuk, I.Karpunina, H.Khodzhibagiyan, A.Kirichenko, V.Kobets, A.Kovalenko, A.Kuznetsov, G.Kuznetsov, O.Kozlov, I.Kulikov, V.Lipchenko, I.Meshkov, V.Mikhaylov, V.Monchinsky, P.Nikitaev, S.Novikov, Yu.Pilipenko, E.Plekhanov, S.Romanov, P.Rukojatkin, V.Sal'nikov, A.Shabunov, V.Shevtsov, V.Shchegolev, V.Seleznev, V.Slepnev, A.Sidorin, G.Sidorov, A.A.Smirnov, A.V.Smirnov, Z.Smirnova, A.Starikov, A.Taratin, A.Tsarenkov, G.Timoshenko, Yu.Vaseneva, B.Vasilishin, N.Vladimirova, V.Volkov. Institute for Nuclear Research and Nuclear Energy BAS, Sofia: I.Geshkov, D.Dinev, I.Tsakov. Institute for Solid State Physics BAS, Sofia: L.Spasov. Institue of Problems of the Measurements, Bratislava: L.Ondrish. Charles University, Prague: M.Finger National Institute of Research and Development for Optoelectronics, Bucharest: R.Savastru Project leader: A.Kovalenko Deputy of the project leader: V.Volkov, G.Trubnikov Project “NUCLOTRON-M” A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

The project “Nuclotron-M” is considered as the first subproject (SP1) of the JINR general future project NICA/MPD ( Nuclotron-based Ion Collider fAcility and Mixed Phase Detector ). The NICA/MPD is aimed at investigation of the mixed phase formation in strongly interacting nuclear matter at extremely high baryon densities and polarization phenomena in few-body nucleon systems. The extension of JINR basic facility capabilities for generation of intense heavy ion and high intensity light polarized nuclear beams, including design and construction of heavy ion collider aimed at reaching the collision energy of  s NN = 4  9 GeV and averaged luminosity of 1·10 27 cm -2 s -1 is necessary for realization of the NICA/MPD. By the present time, different schemes of the NICA were considered. It was shown, the NICA specified parameters (average luminosity, c.m. collision energy, atomic mass range) can be practically reached after: 1)development, modernization and improvement of the Nuclotron systems, 2) design and construction of heavy ion injector, 3) design and construction of heavy ion booster synchrotron and 4) design and construction of the collider rings. “NUCLOTRON-M” A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

“NUCLOTRON-M” A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna NICA/MPD General Scheme

“NUCLOTRON-M” A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna The necessary set of R&D, construction and experimental work that should be done for the Nuclotron modernization is covered by the project.

“NUCLOTRON-M” A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna The project consists of 10 sub-projects having the numbers from SP1.1 to SP1.10 Subproject SP1.1 “Design and construction of highly charged state heavy ion source based on the “KRION” technology” ( leaders: Е.Е. Donets and Е.D.Donets ) Subproject SP1.2 “Modernization of the magnet power supply, quench detection and energy evacuation system ( leaders V.Karpinsky, E.Ivanov ) Subproject SP1.3 “Upgrade of the Nuclotron ring vacuum system” ( leader H. Khodzhibagiyan) Subproject SP1.4 “Development of the accelerator RF system, upgrade of the electronics and the particle capture scheme” ( leaders O.Brovko, A.Eliseev) Subproject SP1.5 “Heavy ion beam extraction at maximum energy “ ( leaders V.Volkov, A.Butenko, A.Taratin) Subproject SP1.6 “Modernization of the Nuclotron control system, beam diagnostics and the accelerator complex parameters” ( leader V.Volkov, B.Vasilishin, V.Andreev) Subproject SP1.7 “Beam transfer lines and radiation shield” (leader P.Rukojatkin) Subproject SP1.8 “Cryogenic supply system” (leaders N.Agapov, V.Batin ) Subproject SP1.9 “Design of the new pre-accelerator with injection and extraction lines” (leaders V.Monchinsky, A.Sidorin, V.Kobets, A.Govorov) Subproject SP1.10 “Design and construction of high intensity polarized deuteron ion source.” (leaders V.Fimushkin, A.Kovalenko)

A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna Development of heavy ion source KRION Construction and test of the new ion source with 6 T solenoid within the coming two years is the main goal of the SP1.1. General view of the ion source and basic operation scheme. The fist Au32+ ion beams have been obtained in October Ionization time was 100 ms. The total intensity was of 1.2*10 9 ions/pulse. The new important feature of the source is capability of operation at high pulse repetition rate in the case of production heavy ions at intermediate charged states, was considered. U 30+ intensity of (4-8)10 10 ions/sec is reached in the case of the pulse repetition rate of 5-10 Hz. Subproject SP1.1 “Design and construction of highly charged state heavy ion source based on the “KRION” technology” ( leaders: Е.Е. Donets and Е.D.Donets )

The fundamental parameter of a KRION-type source is a factor jτ - product of electron current density and ionization time. The jτ value depends, in particular, on the applied external magnetic field. The maximum magnetic field in the existing ion source dont exceed 3 T. Ionization capability of the source and experimental results have been obtained at test bench are presented Fig. 2. Ionization capability (left plot) and experimental results from the ion source KRION-2 on generation of highly charged state gold ions. 1.Design and construction of the new electron-string highly-charged state heavy ion source KRION-6T aimed at generation of heavy ion beams with q/A up to 0.33 (for example Au65+  Au69+). 2.Study of the electron string phenomenon at different conditions in the source working volume ( magnetic field range up to 6 T, energy of electron beam up to 25 keV). Development and optimization of heavy atoms injection into the string and ion-ion cooling process. The further investigation of tubular electron-string ion source 3.Preparation of the existing source KRION-2 to the next run at the Nuclotron aimed at acceleration of the ion beams over atomic mass range of A ~ 100 ( the last decision is iodine I(43+). A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

Basic goal: Provide stable, safe and long operation of the Nuclotron magnetic system at B = 2.1 T The new improved unit for energy damp from the magnets in the case of quench (so-called “thyristor switch”) was designed, constructed and tested. It is necessary to produce and put into operation seven such units for both the dipoles and the quadrupoles power supply circuits. Scheme of the Nuclotron structural magnets power supply (thyristor switches marked with yellow) Subproject SP1.2 “Modernization of the magnet power supply, quench detection and energy evacuation system ( leaders V.Karpinsky, E.Ivanov) The other works on improvement of the other power supplies, namely: for bending magnets of injection channel, beam extraction line from the Nuclotron output window to experimental area, building 205 are also included into the project. A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

At the present time there is no any possibility to pump out gaseous He defusing into the beam pipe through non-hermetic connection near the beam extraction pipe inside the cryostat volume. “NUCLOTRON-M” The averaged presure in the Nuclotron beam pipe measured during the last run in November 2007 is estimated to about p ~ 2-3 ∙ Torr (nitrogen equivalent at 300 K) The target value is p < Torr. Two stages of the system improvement are proposed: Stage 1: necessary development within the “Nuclotron-M” Stage 2: will be considered within the NICA TDR Modernization of the Nuclotron vacuum system; Subproject SP1.3 “Upgrade of the Nuclotron ring vacuum system” ( leader H. Khodzhibagiyan) Necessary equipment for realization of the Stage 1 have been obtained in Installation and commissioning are planned for 2008 A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

Subproject SP1.4 “Development of the accelerator RF system, upgrade of the electronics and the particle capture scheme” ( leaders O.Brovko, A.Eliseev) The problems will be solved are the following : Construction and put into operation the third RF station (to provide acceleration of the particles at the magnetic field ramp up to 2 T/s.) Increase of the Nuclotron longitudinal acceptance by means of design and put into operation flexible (adiabatic) scheme of the particle capture (increase the capture efficiency by a factor of two). Modernization of the system of the frequency/ field control electronics. (This system is especially important because of the planned operation of the accelerator with different ion species within the same run.) Preparation of the project for relativistic heavy ion bunch compression system with the parameters suitable for the NICA. A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

Subproject SP1.5 “Heavy ion beam extraction at maximum energy “ ( leaders V.Volkov, A.Butenko,A.Taratin) Main goal of the sub-project: 1. Modernization of electrostatic septum (ESS) aimed at increase of operation voltage up to 200 kV to provide necessary deflection of the extracted particles up to the magnetic rigidity of the Nuclotron correspond to the NICA specification. (B >1.8 T ) 2. Put into operation additional correcting power supply for the Lambertson magnet of the beam extraction system. 3. Design and realization of heavy ion extraction scheme with the use of a crystal septum. 4. Design of a scheme for fast extraction of compressed heavy ion bunch. The most problematic is the first problem. Maximum ESS voltage is limited at the present time to about 125 kV by the electrical discharges. Within the frames of the sub- project, it is proposed to modify the ESS unit. The use of a crystal septum is considered as additional possibility to provide additional deflection of the extracted ions to the ESS. It could be possible to provide the extraction at maximum accelerator rigidity without replacement of the ESS.

“NUCLOTRON-M” A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna Subproject SP1.6 “Modernization of the Nuclotron control system, beam diagnostics and the accelerator complex parameters” ( leader V.Volkov, B.Vasilishin, V.Andreev) Basic goals: − Development of the Nuclotron control and local network systems aimed at higher reliability, extended possibilities of the existing system, put into operation the advanced industrial PC’s at the “Front End” level; − Upgrade of the sub-system for the accelerator magnetic field control; − Modernization of the sub-system for beam extraction control; − Improvement of operation parameters of the equipment for extracted beam diagnostics ( extended dynamic range of the measured beam intensities, better accuracy, less materials along a beam path are suppose after the planned modernization);

“NUCLOTRON-M” Fig. 5. General scheme of the existing NCS. Nuclotron Control System (NCS) The NCS includes two levels: 1) the “front-end level” (FEL) based on the ADVANTECH industrial computers and 2) the “operator level” (OPL). Modernization of the FEL suppose put into operation of the new modern computers and replace some of the old data collection equipment by the advanced systems produced by National Instruments, CyberResearch, DATATRANSLATION, GaGe, ADVANTECH, ACQUITEK, MEASUREMENT COMPUTING and others. The OPL include work stations at central and local control panels of the accelerator complex. This level provide collection and visualization of the information from sub-systems, store the data archive as well as to provide direct control of accelerator system and their adjustment during the running time. Fig. 6. Structural scheme of the NCS: 50 PC’s (20 Front – End and 30 work station computers are combined in the system). The Nuclotron web-server is available for the outside users. The averaged information traffic through the NCS is reached by the present time to about 400 Kb/s while the maximum traffic value during the active part of the Nuclotron cycle is about 4 Mb/s. The NCS is distributed system, the cable distance reach of about 500 m. Structural scheme of the NCS is shown in Fig. 6. The NCS is based on the local computer network (LCN) of the accelerator complex. The LCN is a sub-unit of the LHE network. Subproject SP1.6 “Modernization of the Nuclotron control system, beam diagnostics and the accelerator complex parameters” ( leader V.Volkov, B.Vasilishin, V.Andreev)

Upgrade of the sub-system for the accelerator magnetic field control Practically all basic parameters will be improved substantially

Subproject SP1.6 “Modernization of the Nuclotron control system, beam diagnostics and the accelerator complex parameters” ( leader V.Volkov, B.Vasilishin, V.Andreev) Beam extraction control The proposed upgrade of the subsystem is based on the use of more powerful elements for the data collection, functional generator and timer units. Structural schemes of the ubsystem and the extracted beam spill feedback control apparatus are shown in Fig.8.1 and Fig The module 1622 YRDA by Cyber Research will be used for the data collection, while the modules PCI-6713 by National Instruments is proposed for the analogue functional generator upgrade. The pilot version of extracted beam spill control equipment is now under operation at the accelerator. The analogues MWPC, digital MWPC and scintillator counters are used for the extracted beam current monitors. Extracted beam diagnostics Coasting bunched beam diagnostics Beam loss monitoring system  The proposed system is based on registration of thermal neutrons flux near the accelerator cryostat. This sub-system contain 64 neutron detectors installed near structural quadrupoles. The test measuring channel was designed and checked.  Improvement of the existing beam closed orbit diagnostic base on 20 BPM's is planned also. Basic goal is extension of the measurements (limited at present by insufficient signal-to-noise ratio due to influence of RF acceleration stations) over the total accelerator cycle. The main disadvantage of the existing system is that all the devices are fixed at the beam line, thus additional material is crossing by the beam. Within the frames of the NICA project the movable measuring blocks will be designed and installed in vacuum boxes of the beam transfer line. R&D work on the beam monitors based on scintillator fibers (SciFi detectors, like developed within the program R&D 17 at CERN) is planned also.

Subproject SP1.7 “Beam transfer lines and radiation shield” (leader P.Rukojatkin) The problems to be solved within the project are the following:  modernization of the main beam extraction and transport line from the nuclotron beam output window to the building 205.  minimization of the material along the beam path; design and put into operation computer system of the magnetic elements power supply control A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

Subproject SP1.8 “Cryogenic supply system” (leaders N.Agapov, V.Batin ) Set of the planned work is the following:  realization of the system for diagnostic and computer control of the existing helium refrigerators KGU-1600/4.5;  design, construction and put into operation the system for re-condensation of a cold gaseous nitrogen evaporated after cooling heat screens of the Nuclotron ring cryogenic modules.  reparation and partial replacement of the cryogenic equipment that have exceeded tolerable operation period. A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna

Design and construction works on heavy ion pre-accelerator chain with injection and extraction beam lines The new heavy ion source KRION-6T, upgrade of pre-accelerators and improvement of vacuum in LU-20 and injection line is supposed within the project “Nuclotron-M”. The existing complex will be used for protons, deuterons, polarized deuterons and light ions (Z/A > 0.3). Subproject SP1.9 “Design of the new pre-accelerator with injection and extraction lines” (leaders V.Monchinsky, A.Sidorin, V.Kobets, A.Govorov) The limiting charge-to-mass ratio of ion accelerated in the LU-20 is q/A  0.3. As it follows from the SP1.1 sub-project description, the possibility of the KRION-type ion source with the magnetic field of 3 T and energy of the electron beam up to 6 keV (existing version of the source) can provide ion beam of 130 Xe 44+, i.e. ions with q/A ≈ Thus, it is possible to perform a test acceleration of heavy ion beam with atomic mass of 130 at the Nuclotron after completion of the work on improvement of vacuum in the accelerator chamber. Acceleration of gold ions will be performed after construction of KRION-6T ion source.

A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna Subproject SP1.9 “Design of the new pre-accelerator with injection and extraction lines” (leaders V.Monchinsky, A.Sidorin, V.Kobets, A.Govorov) The new heavy ion injector is necessary for realization of the NICA project. The approved basic concept of the NICA injector is based on the new ion source KRION-6T and linear accelerator (with pre- accelerator) to accelerate heavy ion beams (q/A  0.12) up to 5-6 MeV/u. Construction of the new linac with pre-accelerator is supposed within the frames of a separate project SP2: “INJECTOR NICA” having the same status as “NUCLOTRON-M”, i.e. subproject of the NICA. Nevertheless, current work on the improvement of the existing injector facility and preparatory work for the new injection line construction are included in the “Nuclotron-M” project. These are the following: optimization of the new injector scheme in the context of the existing buildings, rooms and equipment. R&D, modeling, preparation and approval of the project SP2: “INJECTOR NICA”. (in collaboration with IHEP, Protvino) modernization of the existing linac LU-20, namely: improvement of vacuum pump system including beam transportation line to the nuclotron, development of the linac control system.

A.D.Kovalenko. JINR PAC for Particle Physics, January 17, 2008, Dubna Subproject SP1.10 “Design and construction of high intensity polarized deuteron ion source.” (leaders V.Fimushkin, A.Kovalenko) The main direction of work aimed at increase of polarized beam intensity at the Nuclotron is connected with the design and construction of the new high current polarized ion source (IPSN) based on the equipment of CIPIOS polarized proton and deuteron ion source from Bloomington (Fig.9). The work is carried out in collaboration with INR (Troitsk). The ion source equipment (not completed) was transported to Dubna from IUCF (Indiana University, Bloomington, USA). Some parts of a suitable equipment for the new source were presented from DAPNIA (Saclay ).

Subproject SP1.10 “Design and construction of high intensity polarized deuteron ion source.” (leaders V.Fimushkin, A.Kovalenko)