Applied Physics Researches Division (APRD)

Accelerator Diagnostics Methods Development Group (240/2) History

Posted on Nov 27, 2015

The Low Temperature Lab in Yerevan Physics Institute was established in 1967. The first area of investigations was theoretical and experimental researches of  Fermi surfaces for various metals (were carried out jointly with the IFP, Moscow).

In the beginning of experiments on the Electron Accelerator at YerPhI there were set the experiments using liquid hydrogen and deuterium targets based on externally cooled liquid helium. This approach has been applied worldwide on many Accelerators later. The main condition was to have not more 1 l liquid hydrogen in target in case when operation time of target should be many hundred of hours. The original concept based on liquid helium evaporation heating was developed and the liquefier of hydrogen, heavy hydrogen and neon was manufactured. Made targets successfully worked at accelerator about 10000 hours.

In parallel with this work in 1985 was developed and manufactured continuously working adsorptive cryogenic refrigerator (ACR) without low temperature valves.

A considerable success was achieved in ultralow thermometry. In collaboration with ukrainian physicists (FTINT) was developed and manufactured Crystallization Thermometer based on helium-3 in which the primary signals measurements were done on specially developed in LTL cryogenic electronics.

Another direction of Lab’s activities were the researches of overheated superconducting granules as a Detecting environment. The results of these researches enabled to study the physical aspects of overheated superconducting state in micron-sized granules and demonstrated availability of using superconducting granules for building the detectors of elementary particles.

Researches on Josephson environment in (high temperature superconducting ceramics (HTSC) were another direction. As a result, it was proved that using the HTSC with Josephson environment for building magnetometers sensible as SQUID magnetometers is possible.

The applied researches also attract attention in LTL: superconducting magnets for proton-polarized target, magnet transportation systems for drugs, superconducting magnet systems for high speed public transport. LTL provides also investigations in area of high temperature superconductivity.

LTL infrastructure:

LTL is based on the Building N30 of YerPhI including two experimental halls, mechanical workshop, experimental rooms, stores.

Originally, LTL was created as a laboratory of a technical-experimental bias, therefore, there were a well-equipped machine-shop, a special soldering sector, and two big experimental halls.

Machine shop, including:

    • Milling machine,
    • Turning lathe,
    • Electric-spark lathe,
    • Hydraulic press,
    • Boring mill

2 (Recent results since 1990)

Since 1990 the experiments on the 6 GeV synchrotron were stopped the science area of low temperature physics were switched mainly on the high temperature superconductivity investigations. On the base of developed in Lab original tension sensor (see below) the critical parameters of superconductivity were investigated. On the same principle a special device for magnetic fields gradient measurements was developed.

In frame of INTAS Project (head of Project Ananikyan N.S.) original ultralow thermometer on the vibrating wire base was developed for absolute themperature range about 1 mK.

All these devices were created on the base of unique electromechanical resonators developed in LTL in 1992-1998. The developed methods of fixation of wire ends by hard-alloy clips, decoupling of degrees of freedom on the free end of the wire, usage of defined thermomechanical treatment, choose of wires, magnets and housing materials and development of special methods of wires oscillation generation and measurement allowed achieve unprecedented values of accuracy. The important advantages of properly constructed vibrating wire sensors are inherent long-term stability, high precision and resolution, good reproducibility and small hysteresis. As a result relative accuracy of 10-6 was achieved (accuracy in one-hour interval ± 0.01 Hz,  accuracy in 24-hour interval ± 0.04 Hz,  VWM output signal noise at 10 Hz 0.01 Hz/Rt(Hz)). The equivalent thermal accuracy corresponds to 10-4 K.

Developed type of resonator was used for original vibrating wire sensors and monitors for the measurement of beam transversal characteristics of charged-particle and photon development. By means of these devices, measurements of an electron beam in the Yerevan synchrotron, a proton beam at PETRA (DESY), and a hard x-ray undulator beam at the APS (ANL) have been performed.

The first scanning experiments on a charged beam were done on an electron beam at the Injector of Yerevan Synchrotron with an average current of about 10 nA (after collimation) and an electron energy of 20 MeV.

A series of experiments with the VWS were done on proton beam of the accelerator PETRA at DESY.

The vibrating wire scanner was also tested on an ion beam of energo-mass-analyzer EMAL‑2. Approximately 16 pA of beam current interacted with the wire and a frequency decrement of about 0.15 Hz was measured.

The laser beam was scanned in air by a vibrating wire sensor with two wires sensor.

Hard x-ray flux measurements with a vibrating wire monitor with two wires were conducted at APS.

Taking into account the extreme sensitivity of the vibrating wire sensors was suggested to place the VWS outside of vacuum to detect only very hard x-rays that penetrate the chamber at selected locations. The addition of convective cooling would reduce the response time substantially albeit with reduced sensitivity. The special 5 wire VWM was developed and manufactured. The sensor was mounted on the outboard side of a bending-magnet synchrotron radiation terminating flange in sector 37 at the APS storage ring.