This paper presents the results of the development and implementation of fast wire scanners based on servomotors with a resolver and standard control electronics at a speed of 16 m/s at the U-70 IHEP accelerator. Profilometers are designed to measure the density distribution of proton and carbon beams in the horizontal and vertical planes. The motors of scanners are controlled by servocontrollers through the Copley Motion Explorer CME2 software shell. The beam profile is recorded using scintillation detectors. The beam profile and dimensions were processed using a program developed in the LabVIEW environment. To determine the beam revolution frequency, the fast Fourier transform and the integration of the measured input signal over a given number of beam revolutions are used. The beam parameters are given for a wide range of particle intensities and energies.

A novel slow extraction system for the U-70 synchrotron of the IHEP (Protvino) is presented. The system has been routinely employed since 2013 to extract carbon-nuclei beams with an intermediate energy (455 MeV/nucleon) for applied fixed-target radiobiological research. Issues of the beam dynamics and engineering implementation of the system are considered. The results of experimental beam observations in the U-70 machine are presented, which prove the adequacy of the design approach.

AbstractThe Protvino accelerator facility located in the Moscow region, Russia, is in a good position to offer a rich experimental research program in the field of neutrino physics. Of particular interest is the possibility to direct a neutrino beam from Protvino towards the KM3NeT/ORCA detector, which is currently under construction in the Mediterranean Sea 40 km offshore Toulon, France. This proposal is known as P2O. Thanks to its baseline of 2595 km, this experiment would yield an unparalleled sensitivity to matter effects in the Earth, allowing for the determination of the neutrino mass ordering with a high level of certainty after only a few years of running at a modest beam intensity of$$\approx ~90~\hbox {kW}$$≈90kW. With a prolonged exposure ($$\approx 1500\hbox { kW}\,\,\hbox {year}$$≈1500kWyear), a$$2\sigma $$2σsensitivity to the leptonic CP-violating Dirac phase can be achieved. A second stage of the experiment, comprising a further intensity upgrade of the accelerator complex and a densified version of the ORCA detector (Super-ORCA), would allow for up to a$$6\sigma $$6σsensitivity to CP violation and a$$10^\circ {-}17^\circ $$10∘-17∘resolution on the CP phase after 10 years of running with a 450 kW beam, competitive with other planned experiments. The initial composition and energy spectrum of the neutrino beam would need to be monitored by a near detector, to be constructed several hundred meters downstream from the proton beam target. The same neutrino beam and near detector set-up would also allow for neutrino-nucleus cross section measurements to be performed. A short-baseline sterile neutrino search experiment would also be possible.

This paper briefly outlines the physical substantiation and the engineering implementation of technological systems in the U-70 synchrotron based on controllable noise diffusion of the beam. They include two systems of stochastic slow beam extraction (for high and intermediate energy) and the system of longitudinal noise RF gymnastics designated for flattening the bunch distribution over the azimuth.

A method for analyzing the transverse beam feedback circuit in a ring accelerator and selecting its parameters using the concept of the active beam coupling impedance, which is externally imposed and controlled, is described. This approach is used for the physical substantiation of approaches to upgrading two operational transverse feedback systems that are available in the U-70 synchrotron of the Institute for High Energy Physics, National Research Centre Kurchatov Institute: narrow-band analog and broadband digital systems. Both systems were subjected to deep upgrading, which is based on this method, and were successfully commissioned in 2007 and 2011, respectively. A brief description of their updated engineering implementation is given. The presented experimental results confirm the adequacy of the impedance approach to designing and adjusting the transverse beam feedback circuits in the U-70 synchrotron.

We describe a technique for attaining extended transversally-flat paraxial dose fields with the intermediateenergy carbon beam slowly extracted at the magnetic-field flat-bottom from the IHEP U-70 synchrotron. To this end, a fixed-radius circular beam sweep with the aid of a compact electromechanical wobbler with rotating permanent dipole magnets is applied. A technique for tuning the beam transfer line and the irradiation facility proper at the interim radiobiological workbench with an external fixed target is substantiated. A brief description of its engineering implementation is presented. Results of the successful experimental verification of the technique in question with a carbon nuclear beam from the U-70 machine are reported, in particular, results of the primary radiobiological exercises accomplished in cooperation with the scientists at the MRRC of the Russian Ministry of Healthcare.

A technique for forming square-wave (flat-topped, low-ripple) extraction spills under noise (stochastic) slow extraction of intermediate-energy beam at the magnetic-field flat bottom in the Institute for High Energy Physics (IHEP) U-70 synchrotron is described. For this method to be implemented, an extracted beam current feedback circuit has been developed. The specific feature of the circuit is control of the circulating beam, which diffuses in the transverse (horizontal) direction and does not constitute a linear time-invariant system. The functional block diagram and the feedback tuning procedure are substantiated. The technical characteristics of the feedback system and a brief description of its engineering implementation are presented. Results of the successful system testing with a carbon-nuclei beam in the U-70 machine are reported.

Transverse noise (stochastic) blow-up of the beam in the course of slow particle extraction at the magnetic-field flat bottom in the U-70 synchrotron at the Institute for High Energy Physics has been investigated. The diffusion equation is stated, and the feasible time scale of the transverse (horizontal) noise blow-up of the beam is estimated. The depth of the beam overshoot inward of the edge of the inner energy-degrader target is determined, and the relevant requirements for the target geometry are formulated. Results of experiments with the carbon beam in the U-70 machine are presented.

An optimum tuning procedure of the phase and radial beam feedback loops used in the master oscillator of the accelerating system of the U-70 synchrotron at the Institute for High Energy Physics (IHEP) is described. The recent commissioning of the new digital master oscillator provided a means for using feedback gains, varying in the acceleration cycle, in the course of which the transition energy crossing occurs. This notably improved the quality of the accelerated beam handling. The characteristic equation of the closedloop system is obtained. The complex roots that determine the oscillation eigenmodes are analyzed on its basis, and this allowed one to substantiate practical recommendations on selection of parameters. Results of experiments on the accelerated proton beam with energies of 1.3–50.0 GeV are presented.

Resistive-wall transverse coherent instability shows up as a major adverse factor in running the U70 proton synchrotron of IHEP-Protvino. The 10 th azimuthal spatial harmonic of coherent beam perturbation is the worst one prone to a strong instability. To damp this particular beam mode selectively, a dedicated narrow-band feedback circuit has been developed. All of its hardware (comprising beam pickup and kicker plus analogue processing electronics) is housed in one and the same straight section of the ring lattice, the feedback circuit configuration thus being the local one. Such a straightforward layout minimizes inherent time delays and eases closing the two feedback loops servicing horizontal and vertical directions. The paper contains a brief technical specification of the damping system. Experimental results acquired during its turning on and beam-testing are outlined. GENERALITIES The transverse feedback in question is the so-called Local Feed-Back (LFB) system since all its essential components (beam pickup, HV electrostatic kicker, highpower and low-level processing electronics) are housed closely in the same period #2 of the U70 magnet lattice. All the advantages of such a localized layout were routinely used for years for a base-band cancellation of a resistive wall impedance of a thin corrugated vacuum chamber in the U70 [1], rather than to impose damping per se. Still, in course of the machine upgrade, the thinwall chamber was eventually replaced by a thick-wall smooth one. It hampered the prescribed operation of the feedback because frequency (f) dependence of transverse resistive-wall impedance no longer followed the transfer function vs. f through the open-loop feedback electronics.

The feasibility of developing a system for stochastic (noise) slow extraction from the U-70 proton synchrotron of the Institute for High Energy Physics is substantiated, and the results from its experimental testing are presented. The existing auxiliary 200-MHz RF system (accelerating frequency, 5.5–6 MHz) is used as a longitudinal kicker. This system is driven by the superposition of a deterministic (nonrandom) RF carrier and additive phase noise. The noise gives rise to longitudinal beam diffusion that forces protons into the third-order transverse extraction resonance. The technical constraints inherent in the U-70 machine are taken into account in the proposed scheme. The extraction technique is expected to provide flat-topped spills having a duration of a few seconds and a low contamination with ripple.

Results of research efforts in 2005 that were directed toward developing a system for stochastic (noise) slow extraction of the beam from the U-70 proton synchrotron of the Institute for High Energy Physics are presented. The goal of the study was to develop a full-function prototype of the stochastic slow extraction system and test it on the beam. This prototype, designed for trial operation during machine runs, is capable of producing lengthy flat-topped smooth spills and suppressing their ripple. Approaches to design of the feedback loop that affects the waiting beam stack (which is neither a linear nor time-invariant system) are discussed. A circuit model of the beam being extracted is proposed and analyzed. A dedicated electronic system for beam experiments is described. Results of the beam tests during the U-70 machine run of 2005, which confirm the serviceability of the noise extraction system prototype, are presented.

PROZA-M experiment results as well the proposal of a new spin program with the use of a polarized proton beam are presented. Significant asymmetries were observed in inclusive $\pi^0$ production. The new program proposes to study a wealth of single- and double-spin observables in various reactions using longitudinally and transversely polarized proton beams at U70. The main goal is to define gluon contribution to nucleon spin by measuring double-spin asymmetry in charmonium production.