Aplied Physics Researches Division (APRD)

Accelerator Diagnostics Methods Development Group (240/2) Researches

Posted on Dec 15, 2015

Developments of methods of beam diagnostics and instrumentation for accelerators Beam diagnostics and instrumentation is a typical component of any accelerators based facility aimed to measure and characterize beam parameters (beam intensity, orbit, profiles/emittance, phase/timing, halo, etc.). Progress in accelerator technique requires upgrade of a list of beam parameters – particle energy increase, beam sizes and emittance decrease, specific beam timing, e.g. production of ultrashot bunches, beam halo and electron clouds cleaning, reduction of secondary particle and ions background etc. Commonly upgrade of only one desired parameter lead to necessity to improve of many others. For example the increasing of particles energy requires corresponding decreasing of beam emittance because of most physical processes cross-sections reduction. As a result each upgrade in accelerator needs corresponding development of new concepts in beam diagnostics and instrumentation. The new ideas here claimed from all world accelerator centers. On the other hand area of beam diagnostics and instrumentation does not need catastrophic investments and expenditures. Activity here stipulates by novelty and validity of new ideas and possibility to found the proof-of-principle developed proposals.             Accumulations of YerPhI During the years a lot of concepts were developed aimed to apply in accelerators diagnostics. Some projects were be developed for high energy usage by in principle can be used also for beam diagnostics and instrumentation

  1. YerPhI leading experts (M. Ter-Mikaelian, G.Garibian, A.Amatuni et el) have an significant contribution in development of physical state of transition radiation (TR), especially in the hard part of the TR. A lot of proposals of TR detectors for high energy physics and beam diagnostics were suggested. In fact the one of the resulting usage of transition radiation is OTR (optical TR) monitors widely used in beam 2D visualization. Optical transition radiation detectors serve as a standard tool in most accelerators worldwide. Today is very actual R&D of TR monitors in wavelength range to ultraviolet and soft roentgen.
  2. Ultrashot bunches measurement

2.1. Measuring of femtosecond electron bunches longitudinal profile was proposed on the basis of bunch self electromagnetic field. An electrooptical method was offered to modulate a signal laser beam by coherent part of the bunch electric field (S.Arutunian,  E.Laziev, et al). 2.2. Device for bunch temporal  structure measurement, based on RF deflector (RF streak camera) is proposed (A.Margaryan et al.).

  1. The method of the measurements of angular spread parameters of the electrons and positrons bunches, based on orientation dependence of the passage of the charged particles along the crystal channels and accompanied channeling radiation was pointed out (A.Amatuni, S.Arutunian). Suggestion remain actual for Project of ILC (FNAL).
  2. Precise measurement of absolute energy of the electron beam by using resonant absorption of laser photons in the magnetic field (R. Melikyan)
  3. Vibrating wire technology for beam diagnostics and instrumentation is in progress at last ten years (S.Arutunian, N.Dobrovolsky, M.Mailian, I.Vasiniuk). The operating principle of Vibrating Wire Monitors (VWM) is based on the measurement of the change in the frequency of a heated by measured beam vibrating wire. Because of VWM unprecedented temperature sensitivity such device can be used in very wide range of applications. By this time vibrating wire sensors are successfully applied for electron (YerPhI), proton (PETRA DESY) and ion beams (YerPhI) measurements. VWM can be used for photon beam monitoring with very wide spectral range from deep infrared till to hundreds of keV. Weak laser beams were measured by VWM. First experiments were done in APS ANL for hard X-ray monitoring both in vacuum and in the air. It was proposed also VWM usage for inhomogeneous magnetic field measurement. In 2008 S.Arutunian was recognized as winner of the 2008 Faraday Cup Award in accelerators diagnostics for the development, publication and successful testing of the diagnostic system “Vibrating wire scanner”.
  4. As a beam instrumentation topic can be mentioned the femtosecond transversal deflection of electron beams with help of laser beam (E. Gazazyan, K. Ispirian).
  5. ALICE/YerPhI group has developed Geometry Monitoring System for elements of Muon Spectrometer with accuracy better than 50 micrometers (A.Grigoryan, V.Hovhannisyan, H.Gulkanyan). Developed two-wavelength laser system correct laser path in air and can be successfully used also for accelerators elements alignment.
  6. During last ten years a new polystyrol scintiator system on the basis of new luminofors were developed in YerPhI (V.Gavalyan). Because of larger wave length these scintillators become more radiation stable and can be used in beam visualization with better contrast characteristics. 120 mkm film with inorganic additiuon was successfully used for 20 MeV linear accelerator YerPhI. It is shown that such systems can be useful also for neutron beam diagnostics.
  7. Accelerator diagnostics topic attracts attention of other scientific workers of YerPhI to apply their knowledge in beam diagnostics and instrumentation. For example Gevorkian Zh. proposed a new concept of usage of radiation at particles grazing on rough metal surfaces for beam loss monitor development. K.Ispirian proposed to use carbon nanotubes for beam particle monitoring.

            Perspectives of beam diagnostics and instrumentation in YerPhI Advantages:

  1. Accumulated developments and specialists in wide area of corresponding physics (see above).
  2. Possibility of proof-of-principle experiments on accelerators and other facilities of YerPhI.
  3. Well established communication structure with principle accelerators centers in the world (DESY, JLAB, CERN, APS ANL, …, CANDLE). All these centers can be potentials users of beam diagnostics developments. Some developments are tested and collaboration is continued.
  4. Investments need mostly at state of physical concept and test experiments holding.
  5. Prepared experiments at YerPhI can make a base for concomitant experiments for high energy physics and related topics.