N. S. Azaryan

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.

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.

Superconducting properties of ultra-pure niobium welded joints

An optimal electron-beam welding operating regime for ultra-pure sheet niobium has been developed for use in a superconducting resonator for the International Linear Collider (ILC). The formation of weld joints is studied and their microstructure and microhardness are investigated taking the required geometry of the weld seams into account. Low-temperature electrical measurements in magnetic fields up to 2 T are used to determine the critical parameters of the superconducting transition in the weld area. From the standpoint of the superconducting properties of the resonator, the slight degradation in the characteristics of sheet niobium observed in the thermally affected area (about 10% on average) is not of fundamental importance.

Springer : The temperature stability of 0.005°C for the concrete floor in the CERN Transfer Tunnel #1 hosting the Precision Laser Inclinometer

To reach a sensitivity level of ~10–9 rad for the Precision Laser Inclinometer (PLI) for the registration of the Earth surface angular oscillation in the low frequency band of [10–6 Hz; 1 Hz] the temperature stability of the CERN Transfer Tunnel #1 has been investigated. The daily temperature variation was 0.082°C for the air and 0.005°C for the concrete floor. The last result opened the possibility to observe the Earth surface inclination caused by Moon and Sun if the PLI is thermally stabilized by the massive monolithic concrete floor of the tunnel.

Springer : The compensation of the noise due to angular oscillations of the laser beam in the Precision Laser Inclinometer

An experimental method for the compensation of the noise originated by the laser ray angular oscillations was proposed and experimentally proved for the Precision Laser Inclinometer (PLI). The PLI noise spectral density was reduced by factor 30× and reached 10–8 rad/Hz1/2 level at the frequency of 5 × 10–5 Hz. The angular noise of a laser ray leaving the one-mode optical fiber in the vacuum and in stabilized temperature conditions has been measured. The amplitude of the oscillations for one-day observation reached 0.46 μrad.

Measurement resonance frequency and quality-factor of resonant cavity of Tesla-type in superconducting regime

The article concerns the technique of effective and accurate measurement high quality-factor of resonant cavities of Tesla-type that are used in the ILC in superconducting regime. Presented key outcomes that have been obtained using specially developed computerized measuring system with a set of extra UHF parts.

Manufacture of superconducting niobium cavity parts by hydropercussion punching

A complete cycle of manufacturing all parts of superconducting niobium cavities which comprise two half-cells, two drift tubes, and two flanges each has been developed. The cavity half-cells are manufactured by hydropercussion punching, which has a number of advantages over the instrumental stamping technique. For the first time, the diagram of formability of ultrapure niobium has been experimentally obtained for hydropercussion punching and the key parameters of the process have been determined that ensure complete deep-drawing of workpieces, viz., the value of the limit drawing ratio of ultrapure niobium that is 1.92 at a specific impact energy of 0.42 MJ/m2. The deviations of the half-cell dimensions from the rated values do not exceed 0.1 mm. Production tools required for all manufacturing steps have been created. The parameters of machining of the niobium cavity parts prior to welding have been experimentally established.

Measuring of ultrahigh unloaded Q factor using excitation of a superconducting cavity by the electron beam

A precision method for measuring of ultrahigh unloaded Q factors of superconducting cavities is proposed which is based on the excitation of oscillation in the cavity by electron beam. In this measuring, the cavity is not connected to any external microwave circuit; its unloaded Q factor is determined from the loss of electron-beam power, which can be measured with high accuracy.