Search results for "Protoni"
showing 10 items of 65 documents
The Atomic Cascade in p̄p and Implications for p̄p Annihilations at Rest
1984
Many experiments at LEAR will study the pp interaction at rest via the formation of an atomic bound system of p and p (protonium). Protonium is formed in a highly excited state when the antiproton has been stopped in a target containing gaseous or liquid hydrogen and after it has been captured by a H2 molecule. The subsequent deexcitation process ends with the annihilation of the pp atom from an atomic s-, p- or d-state. The knowledge of the angular momentum of this atomic state is clearly of fundamental importance in the analysis of the annihilation final states. The aim of this contribution is to review the present experimental and theoretical understanding of the de-excitation and annihi…
Constraints on Exotic Spin-Dependent Interactions Between Matter and Antimatter from Antiprotonic Helium Spectroscopy.
2018
Heretofore undiscovered spin-0 or spin-1 bosons can mediate exotic spin-dependent interactions between standard-model particles. Here we carry out the first search for semileptonic spin-dependent interactions between matter and antimatter. We compare theoretical calculations and spectroscopic measurements of the hyperfine structure of antiprotonic helium to constrain exotic spin- and velocity-dependent interactions between electrons and antiprotons.
Co-Rotating Beams of Antiprotons and H- in LEAR and High Resolution Spectroscopy of pp̄ Atoms in Flight
1984
Beams of pp atoms flighting in vacuum with adjustable velocity have been proposed to study the spectroscopy of protonium atoms with high energy resolution (Ae/E down to 10-5) by using differential absorber foils and conventional X-ray detectors for emission spectroscopy and fixed frequency high power radiation sources for induced spectroscopy1. This aproach would lead to an improvement by more than two orders of magnitude versus the possibilities of “conventional” experiments in the field of protonium planned at LEAR2, and would give ways to measure with high accuracy effects of electromagnetic and strong interactions on the atomic levels of protonium.
High-precision mass measurements for the rp-process at JYFLTRAP
2017
The double Penning trap JYFLTRAP at the University of Jyvaskyla has been successfully used to achieve high-precision mass measurements of nuclei involved in the rapid proton-capture (rp) process. A precise mass measurement of 31 Cl is essential to estimate the waiting point condition of 30 S in the rp-process occurring in type I x-ray bursts (XRBs). The mass-excess of 31 C1 measured at JYFLTRAP, -7034.7(3.4) keV, is 15 more precise than the value given in the Atomic Mass Evaluation 2012. The proton separation energy S p determined from the new mass-excess value confirmed that 30 S is a waiting point, with a lower-temperature limit of 0.44 GK. The mass of 52 Co effects both 51 Fe( p,γ ) 52 C…
Excited states in 31S studied via beta decay of 31Cl
2006
The beta decay of 31Cl has been studied with a silicon detector array and a HPGe detector at the IGISOL facility. Previously controversial proton peaks have been confirmed to belong to 31Cl and a new proton group with an energy of 762(14) keV has been found. Proton captures to this state at 6921(15) keV in 31S can have an effect on the reaction rate of 30P(p,γ) in ONe novae. Gamma rays of 1249.1(14) keV and 2234.5(8) keV corresponding to the de-excitations of the first two excited states in 31S have been measured. No beta-delayed protons from the IAS have been observed. peerReviewed
PROTONIUM: The Mainz Cascade Model
1990
Recent experiments at LEAR have studied extensively the properties of antiprotonic hydrogen, often also called protonium.
Cascade of exotic helium atoms
1987
Abstract The cascade of muonic helium and its pressure dependence has been calculated over the whole pressure range from 1×10 −2 to 1×10 3 atm. The calculation does not use any free parameter. The results show good agreement with experimental data.
Confronting the impact parameter dependent JIMWLK evolution with HERA data
2018
The small-$x$ evolution of protons is determined from numerical solutions of the JIMWLK equations, starting from an initial condition at moderate $x$ for a finite size proton. The resulting dipole amplitude is used to calculate the total reduced cross section $\sigma_r$ and charm reduced cross section $\sigma_{rc}$, as well as diffractive vector meson production. We compare results to experimental data from HERA and discuss fundamental problems arising from the regime sensitive to non-perturbative physics. We emphasize that information on the gluonic content of the proton, gluon spatial distributions and correlations over wide ranges in $x$, which can in principle be constrained by our stud…
Lifetime measurements of excited states in $^{169,171,173}$Os: Persistence of anomalous $B(E2)$ ratios in transitional rare earth nuclei in the prese…
2021
International audience; Lifetimes of low-lying excited states in the νi13/2+ bands of the neutron-deficient osmium isotopes 169,171,173Os have been measured for the first time using the recoil-distance Doppler shift and recoil-isomer tagging techniques. An unusually low value is observed for the ratio B(E2;21/2+→17/2+)/B(E2;17/2+→13/2+) in 169Os, similar to the “anomalously” low values of the ratio B(E2;41+→21+)/B(E2;21+→0gs+) previously observed in several transitional rare-earth nuclides with even numbers of neutrons and protons, including the neighbouring 168,170Os. Furthermore, the evolution of B(E2;21/2+→17/2+)/B(E2;17/2+→13/2+) with increasing neutron number in the odd-mass isotopic c…
Diffractive dijet production and Wigner distributions from the color glass condensate
2019
Experimental processes that are sensitive to parton Wigner distributions provide a powerful tool to advance our understanding of proton structure. In this work, we compute gluon Wigner and Husimi distributions of protons within the Color Glass Condensate framework, which includes a spatially dependent McLerran-Venugopalan initial configuration and the explicit numerical solution of the JIMWLK equations. We determine the leading anisotropy of the Wigner and Husimi distributions as a function of the angle between impact parameter and transverse momentum. We study experimental signatures of these angular correlations at a proposed Electron Ion Collider by computing coherent diffractive dijet p…