G. D. Shirkov

Superconducting synchrotron project for hadron therapy

The project of a superconducting medical synchrotron for carbon therapy in the ion energy range from 140 to 400 MeV/n is discussed in this paper. This project is aimed at developing and building a medical synchrotron on the basis of superconducting technologies at JINR under the construction of the Nuclotron accelerator complex. A linear accelerator with alternating phase focusing is proposed for injecting carbon ion into the synchrotron, while it is planned to use a superconducting gantry weighing about 150 t for delivering radiation treatment to patients from all directions.

The precision laser inclinometer long-term measurement in thermo-stabilized conditions (First Experimental Data)

The Precision Laser Inclinometer was tested at thermo-stabilized conditions and the ground angular stability of 1 μrad (observation during 24 h) and 7nrad (observation during 60 min) was measured.

Computation of single-cell superconducting niobium cavity for accelerator of electrons and positrons

Computations of the accelerator section of the International Linear Collider (ILC), which consists of superconducting niobium cavities, are performed for conditions of the maximum energy transfer to electrons that travel along the cavity axis. A mathematical model and software packages are created for the computation of the electric characteristics and profile of a single-cell cavity. A computer-based synthesis of the cavity shape that yields the required electric characteristics is performed. The promising design variants of a single-cell cavity, with which a quality factor of 1010 is provided at a working frequency of 1.3 GHz, are found to optimize the construction and manufacture of a single-cell cavity. The electric characteristics of a chain of single-cell cavities are computed.

The calibration of the Precision Laser Inclinometer

The calibration methods of the two-coordinate Precision Laser Inclinometer are presented. For the inclinometer studied sample of the, the calibration coefficients 630 ± 70 and 531 ± 66 μrad/V have been determined by two independent methods.

The sensitivity limitation by the recording ADC to Laser Fiducial Line and Precision Laser Inclinometer

For metrology set-ups using a laser beam (The Laser Fiducial Line, the Precision Laser Inclinometer) the recording noise has been determined. This noise is limiting the measurement precision of the beam displacement Δx and consequently the precision Δψ of measurement of the beam inclination angle. For a 10 mm laser beam diameter the Δx = ±2.9 × 10–9 m has been obtained. For a one-mode laser beam with a primary diameter of 10 mm and with subsequent focusing a value of Δψ = ±1.7 × 10–11 rad has been found.

Laser Driver for a Photoinjector of an Electron Linear Accelerator (February 2014)

The presented laser driver for a photoinjector of an electron linear accelerator delivers 10-ps long laser pulses with the energy of 1.85 μJ at the wavelength of 262 nm. Laser pulses irradiating with the repetition rate of 10 MHz form the rectangular 800-μ s long pulse trains with 18.5-W mean power inside them. The pulse train repetition rate is 10 Hz. Short-lived absorption centers accumulating in BBO fourth-harmonic generator crystal cause significant distortion of the pulse train envelope. The envelope remains rectangular due to precompensating of these distortions in the fiber acousto-optical modulator with fast varying transmission.

A laser based fiducial line for high precision multipoint alignment system

The next generation of linear colliders is very demanding concerning the alignment tolerances of their components. For the CLIC project, the reference axis of the components will have to be pre-aligned within 10 μm at 1 sigma with respect to a straight line in a sliding window of 200 m. A solution based on stretched wires with wire positioning sensors has been proposed in order to fulfill the alignment requirements in the Conceptual Design Report of the project. This solution has some drawbacks and laser based alternative solutions are under study in order to validate the wire solution and possibly replace it. A new proposal is introduced in this paper, using a laser beam over 150 m as a straight alignment reference, with the objective of having an uncertainty in the determination of its straightness within 10 μm. Sensors coupled to the components to be aligned, would provide after calibration the horizontal and vertical offsets with respect to the laser beam, within a few micrometers, in their coordinate system. The method is based on the laser beam space stabilization effect when a beam propagates in atmospheric air inside a pipe with standing acoustic wave. The principal schemes of corresponding optoelectronics devices and temperature stabilization solutions are also proposed, making probable the extension of the laser fiducial line up to a 500 m length.

Air temperature stabilization in the thermally isolated optical laboratory

For the studies and calibration of optoelectronic components of the high-precision laser based metrology systems the large volume (50 m3) thermoisolated lab based on seismic isolated concrete block is created. The inside lab volume temperature stabilization for the daily observation at 16.5°C is ±0.05°C with ±0.015°C temperature difference between maximal space separated points. This work was initiated by the needs of high-precision alignment of accelerator components of the CLIC, ILC-type colliders.

Comparative analysis of earthquakes data recorded by the innovative Precision Laser Inclinometer instruments and the classic Hydrostatic Level System

The Hydrostatic Level System (HLS) data and the Precision Laser Inclinometer (PLI) instruments data have been comparatively analyzed in the event of surface angular oscillations induced by earthquakes. The comparative data analysis has shown an agreement on the arrival and stop time of earthquakes. The data have been analyzed within the instruments sensitivity ranges having an overlap in frequency intervals.

The innovative method of high accuracy interferometric calibration of the Precision Laser Inclinometer

In this report a high accuracy method for an interferometric calibration of the Precision Laser Inclinometer (PLI) is proposed. The method is based on the simultaneous measurement of: (a) the PLI base calibration slope (angle), set by a piezoelectric positioner, via laser interferometry and (b) the PLI response signal. A calibration coefficient of 322.5 ± 1.9 μrad/V has been determined experimentally in an interval [4 × 10–7, 4 × 10–6] rad in which there is a linear dependence between the PLI-signal and the calibration angle.