Institute For Theoretical And Experimental Physics Research Articles

Laser ion source for semiconductor applications

Carbon implantation can be effectively used for axial minority charge carriers’ lifetime control in various silicon bulk and epitaxial planar structures. When carbon is implanted, more stable recombination centres are formed and silicon is not doped with additional impurities, as for example, when irradiated with protons or helium ions. Economically, such a process competes with alternative methods, and is more efficient for obtaining small lifetimes (several nanoseconds). I-3 ion injector with laser-plasma ion source at Institute for theoretical and experimental physics (ITEP) is used as ion implanter in semiconductors. The ion source uses pulsed CO2 laser setup with radiation-flux density of 1011 W/cm2 at target surface. The ion source produces beams of various ions from solid targets. The generated ion beam is accelerated in the two gap RF resonator at voltage of up to 2 MV per gap. Resulting beam energy is up to 4 MV per charge. Parameters of carbon ion beam generated and used for semiconductor samples irradiation during experiments for axial minority charge carriers lifetime control in various silicon bulk and epitaxial planar structures are presented.

A study of the feasibility of conducting the ELISE and EXL experiments at the ITEP accelerator complex

We report the results of a study into the feasibility of conducting the ELISE and EXL experiments on collisions of nuclei of radioactive fragments with electrons at the Institute for Theoretical and Experimental Physics (ITEP). A scheme for uranium ion acceleration in the ITEP accelerator complex is chosen, and it is shown that uranium ions may be accelerated with an intensity of ∼1 × 1011 ions/s as soon as the complex is modified and a new injector is constructed. The basic parameters of the modified complex are given, and a layout diagram indicating the positions of the target that serves to produce radioactive fragments, the separator, and the storage rings (CR, RESR, NESR, and ER) at the ITEP site is presented.

Betatron resonance crossing during the intense beam bunching

In the process of bunching an intense beam, the betatron oscillation frequency of particles changes due to a growth in their momentum rejection (in the presence of chromaticity) and changes in the Coulomb shift. These changes lead to the intersection of nonlinear betatron resonances. A mathematical model of the dynamics of ions in the process of bunching an intense beam has been built in order to assess the influence of transverse betatron resonances on the motion of particles. This model takes into account the influence of space charge on the longitudinal and transverse oscillations of particles in the presence of one- and two-dimensional betatron resonances. An analysis of the motion of particles near the one- and two-dimensional third-order resonances is given. Results of the numerical simulation of particle losses and emittance growth in the process of bunching an intense beam in the storage ring at the Institute for Theoretical and Experimental Physics (ITEP) are presented.

ITEP MEVVA ion beam for rhenium silicide production

The rhenium silicides are very attractive materials for semiconductor industry. In the Institute for Theoretical and Experimental Physics (ITEP) at the ion source test bench the research program of rhenium silicide production by ion beam implantation are going on. The investigation of silicon wafer after implantation of rhenium ion beam with different energy and with different total dose were carried out by secondary ions mass spectrometry, energy-dispersive x-ray microanalysis, and x-ray diffraction analysis. The first promising results of rhenium silicide film production by high intensity ion beam implantation are presented.

Portable emittance measurement device

In Institute for Theoretical and Experimental Physics (ITEP) the portable emittance measurements device is developed. It provides emittance measurements both with "pepper-pot" and "two slits" methods. Depending on the method of measurements, either slits or pepper-pot mask with scintillator are mounted on the two activators and are installed in two standard Balzer's cross chamber with CF-100 flanges. To match the angle resolution for measured beam, the length of the stainless steel pipe between two crosses changes is adjusted. The description of the device and results of emittance measurements at the ITEP ion source test bench are presented.

Carborane beam from ITEP Bernas ion source for semiconductor implanters

A joint research and development of steady state intense boron ion sources for hundreds of electron-volt ion implanters has been in progress for the past 5 years. The difficulties of extraction and transportation of low energy boron beams can be solved by implanting clusters of boron atoms. In Institute for Theoretical and Experimental Physics (ITEP) the Bernas ion source successfully generated the beam of decaborane ions. The carborane (C(2)B(10)H(12)) ion beam is more attractive material due to its better thermal stability. The results of carborane ion beam generation are presented. The result of the beam implantation into the silicon wafer is presented as well.

Correction of SiPM temperature dependencies

The performance of a high granular analogue hadronic calorimeter (AHCAL) using scintillator tiles with built-in Silicon Photomultiplier (SiPM) readout is reported. A muon beam is used for the minimum ionizing particle (MIP) based calibration of the single cells. The calibration chain including corrections for the non-linearity of the SiPM is presented. The voltage and temperature dependencies of the SiPM signal have been investigated using the versatile LED system of the AHCAL. Monitoring and correction methods are discussed. Measurements from the operation 2006 and 2007 at the CERN SPS test beam and data provided by the Institute for Theoretical and Experimental Physics (ITEP) in Moscow are compared.

Undergraduate participation in accelerator-based experiments in baryon spectroscopy

ACU physicists have been involved in measurements of meson–nucleon scattering, baryon spectroscopy, for over 25 years. The incorporation of a large number of undergraduates has been an integral part of this effort at eight accelerator laboratories in the US, Europe and Japan. Present projects involve data analysis of the completed Crystal Ball program at Brookhaven National Laboratory, preparation for a future measurement to investigate nucleon resonances at the Institute for Theoretical and Experimental Physics (ITEP) in Moscow, and development of proposals at the MIPP facility at Fermilab and J-PARC in Japan. A collaboration of partial wave analysis (PWA) of these data is also underway. An overview of the undergraduate participation will be presented with a discussion of both successes and failures.

Ian Ilyich Kogan

Ian Ilyich Kogan, reader in theoretical physics at the University of Oxford and a fellow of Balliol College, died of a heart attack in Trieste, Italy, on 4 June 2003. Ian was a greatly talented physicist of boundless energy and enthusiasm with a legion of close friends and collaborators. He made major contributions to physics, including being codiscoverer of phase transitions in strings, of logarithmic conformal field theory, and of the theory of multigravity. It is fair to say that Ian’s impact shaped the direction of research in those areas.Ian was born into a Jewish family on 14 September 1958 in Glazov, a small town in the Northern Urals, far away from all the cultural centers of what was then the Soviet Union. All life in that town revolved around a uranium plant, where Ian’s parents worked for 41 years. At age 16, Ian began his life’s journey; accompanied by his father, he went to Moscow to sit the entrance examinations at the Moscow Institute of Physics and Technology (MIPT).Despite the then common prejudice against Jews, Ian obtained admission to the MIPT. In 1981, he graduated with an MS in theoretical and mathematical physics. He then moved to the Institute for Theoretical and Experimental Physics (ITEP) for his doctoral studies in theoretical physics under the supervision of Boris Ioffe and Karen Ter-Martirosyan. He received his PhD in 1985 for his studies on hadronic form factors and the coupling constants from the quantum chromodynamic sum rules. Ian stayed on at the ITEP in a junior staff position. He began his professional career studying QCD, the theory of hadronic physics. Although he always retained his interest in QCD, his scientific horizons rapidly expanded. He started to branch out into string theory, believed by many to be the most fundamental theory of nature capable of unifying all the fundamental interactions. While at the ITEP, Ian made major contributions to the understanding of the behavior of strings at high temperatures and became an early explorer of Chern-Simons electrodynamics.Leaving Russia in 1991, Ian went to the University of British Columbia and then to Princeton University as a visiting professor, before moving in October 1994 to Oxford as a university lecturer in theoretical physics and fellow of Balliol College. In 2001, he became a British citizen. Ian’s span of interests was phenomenal, and he made significant contributions across a wide range of fields. He made notable advances in Liouville theory, extra-dimension scenarios, black holes, anyons, chiral condensates, and high-temperature field and string theory. His interests extended beyond physics, too, to the application of the techniques of theoretical physics to the analysis of risk assessment in the financial markets. Ian’s knowledge of his subject was encyclopedic. By the time he arrived in Oxford, his command of physics was such that undergraduate and graduate students and his colleagues were invariably treated to a spontaneous solution to a problem or explanation of a perplexing matter. In seminars covering almost any subject, he would engage the speaker in a lively and focused debate. His presence at Oxford added immeasurably to the intellectual activity.Ian circumnavigated theoretical physics. And everywhere, he left his imprint. He had the spirit of a pioneer and a scout—always at the front line of research and quite often ahead of the front line. He generously shared his ideas, which were stimulating and encouraging, with students and collaborators. He published some 200 scientific papers with nearly 60 collaborators around the globe. Ian’s death is a tragedy for the entire physics community, but his many friends and colleagues treasure the privilege it has been to know such a vibrant spirit.Ian Ilyich KoganPPT|High resolution© 2004 American Institute of Physics.

Two approaches to electron beam enhancement of the metal vapor vacuum arc ion source

Conclusive demonstration of electron-beam enhancement of ion charge states for the Metal Vapor Vacuum Arc (MEVVA) ion source was recently achieved using an external electron beam (E-MEVVA) in experiments performed jointly among the Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia, the High Current Electronics Institute (HCEI), Tomsk, Russia, and Brookhaven National Laboratory (BNL), USA. The E-MEVVA experiments were performed in Moscow and Tomsk with nearly the same design of ion sources. Results for lead and bismuth cathodes yielded maximum ion charge states of Pb7+ and Bi8+ for E-MEVVA, as compared to Pb2+ and Bi2+ for conventional MEVVA operation. Additional encouraging results were also obtained using a Z-discharge to produce an internal electron-beam (Z-MEVVA and LIZ-MEV).

Beam losses in heavy ion drivers

While beam loss issues have hardly been considered in detail for heavy ion fusion scenarios, recent heavy ion machine developments in different labs (European Organization for Nuclear Research(CERN), Gesellschaft für Schwerionenforschung (GSI), Institute for Theoretical and Experimental Physics (ITEP), Relativistic Heavy-Ion Collider (RHIC)) have shown the great importance of beam current limitations due to ion losses. Two aspects of beam losses in heavy ion accelerators are theoretically considered: (1) secondary neutron production due to lost ions, and (2) vacuum pressure instability due to charge exchange losses. Calculations are compared and found to be in good agreement with measured data. The application to a Heavy-Ion Driven Inertial Fusion (HIDIF) scenario is discussed.

Direct searches for neutrino mass

At present there is no positive experimental evidence that neutrinos have mass. Nevertheless, searches for neutrino mass continue, largely because the consequences of neutrinos having mass would be quite profound. In particular, the discovery of a non-zero neutrino mass would be a clear indication of physics beyond the current particle-physics standard model. In addition, neutrinos, if they have mass, remain viable candidates for the non-baryonic dark matter known to permeate galaxies. The current status of the experimental efforts searching for neutrino mass will be reviewed. In particular, it will be shown that the most recent tritium beta decay searches for neutrino mass clearly rule out the non-zero neutrino mass result first reported in 1980 by the Institute for Theoretical and Experimental Physics (ITEP) in Moscow. However, a troubling feature of these same recent results is that they all have best fits to neutrino mass squared that are negative. The significance of these negative neutrino mass squared results will be explored.

Use of USSR Proton Accelerators for Medical Purposes

Proton beams of the Joint Institute for Nuclear Research (LNP, JINR) Dubna synchrocyclotron and of the proton synchrotron of the Institute for Theoretical and Experimental Physics (ITEP) Moscow have been used for medical and biological purposes since 1967. 58 patients in JINR and 163 in ITEP with various types of malignant tumors have been treated. Results of clinical research showed that use of high energy protons for treatment of malignant tumors is quite expedient and may serve as a good approach developing better means for irradiation in oncological therapy. Proposals for proton and meson beams at the JINR high intensity phasotron and for proton beams at the ITEP medical and biological center are discussed. The ITEP center will consist of 4 cabins for therapy and 2 cabins for radiobiological research, which will permit to treat ~ 100 patients per day.