Nucleon form factor measurements in Mainz: past and future

2007 ◽  
Vol 85 (5) ◽  
pp. 419-427
Author(s):  
Jan C Bernauer

The form factors of protons and neutrons provide a natural and direct insight into their internal structure. They were a main research goal in the nuclear physics program of the Universitat Mainz, which led to some of the most precise measurements to date. This article gives an overview, starting from the very first experiments at the now obsolete linear accelerator and ending at the exhaustive experiments currently underway at the MAMI facilities. PACS Nos.: 14.20.Dh, –13.40.Gp, –25.30.Bf


2018 ◽  
Vol 27 (07) ◽  
pp. 1830004 ◽  
Author(s):  
Kurt Aulenbacher ◽  
Eugene Chudakov ◽  
David Gaskell ◽  
Joseph Grames ◽  
Kent D. Paschke

Polarized electron beams have played an important role in scattering experiments at moderate to high beam energies. Historically, these experiments have been primarily targeted at studying hadronic structure — from the quark contribution to the spin structure of protons and neutrons, to nucleon elastic form factors, as well as contributions to these elastic form factors from (strange) sea quarks. Other experiments have aimed to place constraints on new physics beyond the Standard Model. For most experiments, knowledge of the magnitude of the electron beam polarization has not been a limiting systematic uncertainty, with only moderately precise beam polarimetry requirements. However, a new generation of experiments will require extremely precise measurements of the beam polarization, significantly better than 1%. This paper will review standard electron beam polarimetry techniques and possible future technologies, with an emphasis on the ever-improving precision that is being driven by the requirements of electron scattering experiments.



Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 799
Author(s):  
Justyna Miedzianowska ◽  
Marcin Masłowski ◽  
Przemysław Rybiński ◽  
Krzysztof Strzelec

Increasingly, raw materials of natural origin are used as fillers in polymer composites. Such biocomposites have satisfactory properties. To ensure above-average functional properties, modifications of biofillers with other materials are also used. The presented research work aimed to produce and characterize elastomeric materials with a straw-based filler and four different types of montmorillonite. The main research goal was to obtain improved functional parameters of vulcanizates based on natural rubber. A series of composites filled with straw and certain types of modified and unmodified nano-clays in various ratios and amounts were prepared. Then, they were subjected to a series of tests to assess the impact of the hybrids used on the final product. It has been shown that the addition of optimal amounts of biofillers can, inter alia, increase the tensile strength of the composite, improve damping properties, extend the burning time of the material and affect the course of vulcanization or cross-linking density.



2017 ◽  
Vol 41 (3) ◽  
pp. 555-583 ◽  
Author(s):  
Niels Geiger

This article is devoted to the issue of operationalizing and empirically measuring the development of behavioral economics, focusing on trends in the academic literature. The main research goal is to provide a quantitative, bibliometric assessment to answer the question of whether the relative importance of behavioral economics has increased over the past decades. After an introduction and a short summary of the history of behavioral economics, several studies are laid out and evaluated. The results generally provide a quantitative confirmation of the story of a rise of behavioral economics that can be found in the literature, and add some notable additional insights.





Author(s):  
H. Kreckel ◽  
O. Novotný ◽  
A. Wolf

The new Cryogenic Storage Ring at the Max Planck Institute for Nuclear Physics (Heidelberg, Germany) has recently become operational. One of the main research areas foreseen for this unique facility is astrochemical studies with cold molecular ions. The spontaneous radiative cooling of the prototype interstellar molecule CH + to its lowest rotational states has been demonstrated by photodissociation spectroscopy, paving the way for experiments under true interstellar conditions. To this end, a low-energy electron cooler and a neutral atom beam set-up for merged beams studies have been constructed. These experiments have the potential to provide energy-resolved rate coefficients for fundamental astrochemical processes involving state-selected molecular ions. The main target reactions include some of the key processes of interstellar chemistry, such as the electron recombination of H 3 + , charge exchange between H 2 + and H, or the formation of CH + in collisions of triatomic hydrogen ions and C atoms. This article is part of a discussion meeting issue ‘Advances in hydrogen molecular ions: H 3 + , H 5 + and beyond’.



2019 ◽  
Vol 214 ◽  
pp. 05027 ◽  
Author(s):  
Pavel Batyuk ◽  
Konstantin Gertsenberger ◽  
Sergey Merts ◽  
Oleg Rogachevsky

A new generation of experiments for the relativistic nuclear physics is expected to be started up in the nearest years at the Nuclotron-based Ion Collider fAcility (NICA) under construction at the Joint Institute for Nuclear Research in Dubna. The main part of the facility is the essentially modernized accelerator Nuclotron. BM@N (Baryonic Matter at Nuclotron) is considered as a first stage towards realization of physics program available at NICA. It is a fixed target experiment aimed to work with the Nuclotron extracted beams of different species. The experiment had a set of technical runs since 2015. For a successful realization of the BM@N physics program, a well developed and tested software for simulation, digitization, reconstruction and analysis of collision events and other additional tasks is of utmost importance. The BmnRoot software developed in order to operate the mentioned tasks is described in this article. It includes modules for data digitizing obtained from BM@N detector systems, realistic simulation of signals in detectors, alignment of detectors, reconstruction of multiparticle interaction events, as well as all necessary systems for maintaining the databases of the experiment, visualization and providing information support for the experiment.



2020 ◽  
pp. PHYTO-06-20-023
Author(s):  
Laura S. Bautista-Jalón ◽  
Omer Frenkel ◽  
Leah Tsror (Lahkim) ◽  
Glenna M. Malcolm ◽  
Beth K. Gugino ◽  
...  

Verticillium dahliae is a soilborne fungal pathogen affecting many economically important crops that can also infect weeds and rotational crops with no apparent disease symptoms. The main research goal was to test the hypothesis that V. dahliae populations recovered from asymptomatic rotational crops and weed species are evolutionarily and genetically distinct from symptomatic hosts. We collected V. dahliae isolates from symptomatic and asymptomatic hosts growing in fields with histories of Verticillium wilt of potato in Israel and Pennsylvania (United States), and used genotyping-by-sequencing to analyze the evolutionary history and genetic differentiation between populations of different hosts. A phylogeny inferred from 26,934 single-nucleotide polymorphisms (SNPs) in 126 V. dahliae isolates displayed a highly clonal structure correlated with vegetative compatibility groups, and isolates grouped in lineages 2A, 2B824, 4A, and 4B, with 77% of the isolates in lineage 4B. The lineages identified in this study were differentiated by host of origin; we found 2A, 2B824, and 4A only in symptomatic hosts but isolates from asymptomatic hosts (weeds, oat, and sorghum) grouped exclusively within lineage 4B, and were genetically indistinguishable from 4B isolates sampled from symptomatic hosts (potato, eggplant, and avocado). Using coalescent analysis of 158 SNPs of lineage 4B, we inferred a genealogy with clades that correlated with geographic origin. In contrast, isolates from asymptomatic and symptomatic hosts shared some of the same haplotypes and were not differentiated. We conclude that asymptomatic weeds and rotational hosts may be potential reservoirs for V. dahliae populations of lineage 4B, which are pathogenic to many cultivated hosts.



Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 98
Author(s):  
Astrid Morreale

Quarks and gluons are the fundamental constituents of nucleons. Their interactions rather than their mass are responsible for 99 % of the mass of all visible matter in the universe. Measuring the fundamental properties of matter has had a large impact on our understanding of the nucleon structure and it has given us decades of research and technological innovation. Despite the large number of discoveries made, many fundamental questions remain open and in need of a new and more precise generation of measurements. The future Electron Ion Collider (EIC) will be a machine dedicated to hadron structure research. It will study the content of protons and neutrons in a largely unexplored regime in which gluons are expected to dominate and eventually saturate. While the EIC will be the machine of choice to quantify this regime, recent surprising results from the heavy ion community have begun to exhibit similar signatures as those expected from a regime dominated by gluons. Many of the heavy ion results that will be discussed in this document highlight the kinematic limitations of hadron–hadron and hadron–nucleus collisions. The reliability of using as a reference proton–proton (pp) and proton–ion (pA) collisions to quantify and disentangle vacuum and Cold Nuclear Matter (CNM) effects from those proceeding from a Quark Gluon Plasma (QGP) may be under question. A selection of relevant pp and pA results which highlight the need of an EIC will be presented.



2020 ◽  
Vol 35 (10) ◽  
pp. 2050062
Author(s):  
Abdullah Engin Çalık ◽  
Kaan Manisa ◽  
Ahmet Biçer ◽  
Mehmet Erdoğan ◽  
Mürsel Şen ◽  
...  

Photonuclear reactions have great importance in understanding the structure of the nuclei. These reactions, performed using the gamma rays obtained by way of bremsstrahlung, are a standard nuclear physics experiment. In this study, a non-enriched barium sample was activated for the first time by using a clinical linear accelerator (cLINACs). The spectrum of barium radioisotopes was obtained by using a gamma spectrometry with a high purity germanium (HPGe) detector. The obtained spectroscopic data were analyzed and energy levels and half-life values together with their uncertainties were obtained. Some energy levels and half-lives of [Formula: see text]Ba were determined with more precision than those of literature values.



1985 ◽  
Author(s):  
C. Rioux ◽  
R. Roy ◽  
R. J. Slobodrian


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