Petr S. Stepanov

• PhD graduate in Photochemical Sciences
• PostDoc Position at Catholic University of America

This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams,...

We performed feasibility studies for various measurements that are related to unpolarized TMD distribution and fragmentation functions. The processes studied include semi-inclusive Deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The single hadron cross sections and mult...

We performed feasibility studies for various single transverse spin measurements that are related to the Sivers effect, transversity and the tensor charge, and the Collins fragmentation function. The processes studied include semi-inclusive deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the sca...

Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction s...

The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detec...

The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow \mu$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to \tau$ CLFV...

We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range fr...

The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably,...

The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECC...

Understanding the irradiation-induced defects in oxides is of interest for a wide range of applications. ZnO is an interesting oxide with mixed ionic and covalent bonding that contains a variety of point defect structures-making it an excellent model for studying irradiation-induced defects and their impact on properties. Here, we investigate the e...

The questions of how the bulk of the Universe’s visible mass emerges and how it is manifest in the existence and properties of hadrons are profound, and probe the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be key to a further understanding of the emergent mass and structure mechanisms. These meso...

Current trends in development of positron annihilation tomography (change-over to total body tomography, new image reconstruction methods based on Time-of-Flight techniques and 3γ annihilation events) are discussed. They open up unique possibilities of identifying both the annihilation point of Ps atoms and their lifetime in the tissues of the orga...

This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams,...

How the bulk of the Universe's visible mass emerges and how it is manifest in the existence and properties of hadrons are profound questions that probe into the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be the key to the further understanding of the emergent mass and structure mechanisms. These...

The interaction of positronium (Ps) with molecular oxygen dissolved in liquids is experimentally investigated. A computer software has been developed for fitting the positron annihilation lifetime spectra in liquids using parameters with clear physical meaning: rate constants of the Ps chemical reactions, annihilation rate constants of the differen...

Software that allows fitting positron lifetime (LT) and coincidence Doppler broadened (CDB) positron annihilation spectra of nanodispersed dielectric powders is developed. Computer program takes into account following effects: possibility of e⁺ trapping by vacancy-type defects, formation of the surface-bound e⁺ states, formation and thermalization...

A model that allows interpretation of positron annihilation spectra (LT and CDB) in nanodispersed dielectric powders is developed. Model takes into account e⁺ capture by vacancy-type defects, formation of e⁺ surface-bound states, as well as the formation of quasi-free positronium (inside crystallites) which may escape into intergranular space where...

Transparent ceramics are emerging as future materials for lasers, scintillation, and illumination. In this paper, an interesting and surprising phenomenon in YAG transparent ceramics is reported. UV light leads to significant changes in the microstructure of open volume defects and nano clusters as well as in the optical properties. Light-induced l...

Room temperature photoconductivity measurements have been carried out on various as-grown SrTiO3 single crystals provided from different suppliers. We observed an increase in the conductivity of samples based on photon energy and photon intensity. While low energy photons decreased the conductivity, photons with energy close to the band gap of SrTi...

A digital coincidence Doppler broadening (CDB) spectrometer consisting of two HPGe detectors is assembled; the energy resolution of each detector is 1.1 keV at energies near the annihilation line. Two desktop applications for CDB spectra processing are developed. TLIST Processor converts two-dimensional CDB spectra into one-dimensional spectra. Ano...

State Univ — The origins of the luminescence and scintillation properties of zinc oxide are studied by means of photo – luminescence (PL), X – ray induced lumines-cence (XRIL) [Review of Scientific Instruments 83, 103112(2012)], gamma – induced positron spectroscopy (GIPS), and scintillation counting measurements such as coupling the ZnO crystals t...

The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided...

We have estimated a local heating which takes place owing to the ionization energy losses at the terminal part of a fast positron track and at nano-vicinities of the 57Fe Mössbauer nuclei in case of the emission Mössbauer spectroscopy. It is shown that in experiments close to the melting point one may expect local melting near the probe species.

Scintillation properties are often studied by photo-luminescence (PL) and scintillation measurements. In this work, we combine X-ray-induced luminescence (XRIL) spectroscopy [Review of Scientific Instruments 83, 103112 (2012)] with PL and standard scintillation measurements to give insight into the scintillation properties of un-doped ZnO single cr...

Positron ionization slowing down, formation of the positron track, reactions of e+ with track species and its interaction with a scavenger on a subpicosecond timescale, including the process of the positronium formation process are discussed. Interpretation of the positron annihilation lifetime data on positronium formation in aqueous solutions of...

Luminescence and scintillation in ZnO single crystals were measured by photoluminescence and X-ray-induced luminescence (XRIL). XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. The origin of green emission, the dominan...

The potential of positron spectroscopy for identification of nanosized structures in liquid mixtures, which is a difficult problem that still remains a challenge in physical chemistry of liquids, was demonstrated. The water- n-propanol mixtures were chosen as an example. An analysis of the concentration dependences of the mean lifetime of ortho-pos...

Analysis of the o-Ps lifetimes concentration dependences in water-propanol mixtures (with and without CoCl2 additive) shows that this mixture looks like an emulsion of alcohol micelles in water at propanol mole fractions 0.1-0.4.

Investigation of the local heating effect at the terminal part of a fast positron track sheds light on the accumulation of defects in a frozen medium close to its melting point. Estimations of the formation energies of the structural defects which may trap the Ps atom as well as a contribution of these defects to the enthalpy of fusion are obtained...

This chapter reviews the following items: 1. Energy deposition and track structure of fast positrons: ionization slowing down, number of ion-electron pairs, typical sizes, thermalization, electrostatic interaction between e+ and its blob, effect of local heating; 2. Positronium formation in condensed media: the Ore model, quasifree Ps state, intrat...

A self consistent interpretation of the positron lifetime experiments in water at different temperatures (2-93 0C) and magnetic fields (H ≤ 2 T) is given. By using the blob model of Ps for-mation we have obtained the contact density in the positronium atom in water, which is in agree-ment with the previous measurements.

A change in the energy E max of the solvated electron, which corresponds to the maximum intensity of its optical absorption spectrum in the homologous series of alcohols seems to be alternating in character. The effect is retained upon elevation of pressure up to 2 kbar but disappears in alcohols frozen at 77 K. Probably, the effect also holds for...