scholarly journals Study of pp → 𝚵+ ΛK- with the PANDA Detector

2020 ◽  
Vol 241 ◽  
pp. 03004
Author(s):  
Jennifer Pütz ◽  
Albrecht Gillitzer ◽  
James Ritman ◽  
Tobias Stockmanns
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Large Fraction ◽  
Experimental Studies ◽  
Final States ◽  
Proton Collisions ◽  
Baryon Spectroscopy ◽  
Excitation Pattern ◽  
Insight Into ◽  
Panda Detector

For a deeper insight into the mechanisms of non-perturbative QCD it is essential to understand the excitation pattern of baryons. Up to now only the nucleon excitation spectrum has been subject to systematic experimental studies, while very little is known on excited states of double or triple strange baryons. In studies of antiproton-proton collisions the PANDA experiment is well-suited for a comprehensive baryon spectroscopy program in the multi-strange sector. A large fraction of the inelastic pp cross section is associated to final states with a baryon-antibaryon pair together with additional mesons, giving access to excited states both in the baryon and the antibaryon channel. For final states containing a 𝚵+ 𝚵- pair, cross sections up to µb are expected, corresponding to production rates of ~ 106/d at a luminosity L = 1031 cm-2 s-1. This study focuses on excited 𝚵- states decaying into ΛK-. A strategy to reconstruct the reaction pp → 𝚵+ 𝚵* and its charge conjugate channel with the PANDA detector will be presented.

scholarly journals STRUCTURE FUNCTIONS

2009 ◽  
Vol 24 (06) ◽  
pp. 1069-1086 ◽  
Author(s):  
CRISTINEL DIACONU
Keyword(s):  
Cross Sections ◽  
Structure Functions ◽  
Distribution Functions ◽  
Final States ◽  
Parton Distribution Functions ◽  
Proton Antiproton ◽  
Proton Proton ◽  
Proton Collisions ◽  
Bjorken X ◽  
Proton Proton Collisions

Recent progress in the understanding of the nucleon is presented. The unpolarized structure functions are obtained with unprecedented precision from the combined H1 and ZEUS data and are used to extract proton parton distribution functions via NLO QCD fits. The obtained parametrization displays an improved precision, in particular at low Bjorken x, and leads to precise predictions of cross-sections for LHC phenomena. Recent data from proton–antiproton collisions at Tevatron indicate further precise constraints at large Bjorken x. The flavor content of the proton is further studied using final states with charm and beauty in DIS ep and [Formula: see text] collisions. Data from polarized DIS or proton–proton collisions are used to test the spin structure of the proton and to constrain the polarized parton distributions.

DOUBLE EXCITATION IN PROTON–HELIUM COLLISIONS

1995 ◽  
Vol 09 (25) ◽  
pp. 3269-3301 ◽  
Author(s):  
M. SCHULZ
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Experimental Studies ◽  
Projectile Energy ◽  
Interference Effects ◽  
Double Excitation ◽  
Doubly Excited States ◽  
Doubly Excited ◽  
Excitation Mechanisms ◽  
The Cross

Theoretical and experimental studies on double excitation in proton–helium collisions are reviewed. Two theoretical approaches, which are common in the treatment of atomic collision processes, are described: perturbative approaches and the close coupling method. Experimentally, double excitation has mainly been studied by spectroscopy of the autoionized electrons emitted by the decay of the doubly excited states and by projectile energy-loss spectroscopy. The results emerging from the theoretical and experimental studies include the following points: first, the coupling of the doubly excited states to the continuum is very important in the electron spectra leading to pronounced interference effects. Second, double excitation mechanisms involving the electron–electron interaction are dominant except for low projectile energies. Third, interference effects between various double excitation mechanisms appear to be insignificant in the cross-sections differential in the electron emission angle, but might be important under certain conditions in the cross-sections differential in the projectile scattering angle.

scholarly journals Study of excited $$\varvec{\varXi }$$ baryons with the $$\overline{\text{ P }}$$ANDA detector

2021 ◽  
Vol 57 (4) ◽  
Author(s):  
G. Barucca ◽  
F. Davì ◽  
G. Lancioni ◽  
P. Mengucci ◽  
L. Montalto ◽  
...  
Keyword(s):  
Cross Sections ◽  
Production Cross ◽  
Direct Access ◽  
Final States ◽  
Excitation Spectra ◽  
Decay Modes ◽  
Baryon Spectrum ◽  
Detector Acceptance ◽  
Independent Information ◽  
Insight Into

AbstractThe study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards $$N^*$$ N ∗ and $$\varDelta $$ Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the $$N^*$$ N ∗ and $$\varDelta $$ Δ spectra. The future antiproton experiment $$\overline{\text{ P }}$$ P ¯ ANDA will provide direct access to final states containing a $${\overline{\varXi }}\varXi $$ Ξ ¯ Ξ pair, for which production cross sections up to $$\mu \text{ b }$$ μ b are expected in $$\bar{\text{ p }}$$ p ¯ p reactions. With a luminosity of $$L=10^{31}$$ L = 10 31 cm$$^{-2}$$ - 2 s$$^{-1}$$ - 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of $$\sim 10^6\, \text{ events }/\text{day }$$ ∼ 10 6 events / day . With a nearly $$4\pi $$ 4 π detector acceptance, $$\overline{\text{ P }}$$ P ¯ ANDA will thus be a hyperon factory. In this study, reactions of the type $$\bar{\text{ p }}$$ p ¯ p $$\rightarrow $$ → $${\overline{\varXi }}^{+}$$ Ξ ¯ + $$\varXi ^{*-}$$ Ξ ∗ - as well as $$\bar{\text{ p }}$$ p ¯ p $$\rightarrow $$ → $${\overline{\varXi }}^{*+}$$ Ξ ¯ ∗ + $$\varXi ^{-}$$ Ξ - with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.

scholarly journals E/Z Molecular Photoswitches Activated by Two-Photon Absorption: Comparison between Different Families

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7379
Author(s):  
Marco Marazzi ◽  
Cristina García-Iriepa ◽  
Carlos Benitez-Martin ◽  
Francisco Najera ◽  
Antonio Monari ◽  
...  
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Experimental Studies ◽  
Substitution Effect ◽  
Photon Absorption ◽  
Spatial Control ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Absorption Energy ◽  
Donor Acceptor

Nonlinear optical techniques as two-photon absorption (TPA) have raised relevant interest within the last years due to the capability to excite chromophores with photons of wavelength equal to only half of the corresponding one-photon absorption energy. At the same time, its probability being proportional to the square of the light source intensity, it allows a better spatial control of the light-induced phenomenon. Although a consistent number of experimental studies focus on increasing the TPA cross section, very few of them are devoted to the study of photochemical phenomena induced by TPA. Here, we show a design strategy to find suitable E/Z photoswitches that can be activated by TPA. A theoretical approach is followed to predict the TPA cross sections related to different excited states of various photoswitches’ families, finally concluding that protonated Schiff-bases (retinal)-like photoswitches outperform compared to the others. The donor-acceptor substitution effect is therefore rationalized for the successful TPA activatable photoswitch, in order to maximize its properties, finally also forecasting a possible application in optogenetics. Some experimental measurements are also carried out to support our conclusions.

3-D reconstruction and analysis of mammalian mitotic spindle structure

1992 ◽  
Vol 50 (1) ◽  
pp. 578-579
Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh
Keyword(s):  
Cross Sections ◽  
Mitotic Spindle ◽  
Experimental Studies ◽  
Video Camera ◽  
Three Dimensions ◽  
Mitotic Spindles ◽  
Black And White ◽  
Reconstruction Methods ◽  
Spindle Structure ◽  
Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

IN SITU AND PILOT ORGAN PERFUSION TECHNIQUES FOR THE STUDY OF METABOLIC DYNAMICS

1972 ◽  
Vol 68 (2_Supplb) ◽  
pp. S9-S25 ◽  
Author(s):  
John Urquhart ◽  
Nancy Keller
Keyword(s):  
Cardiac Output ◽  
Large Fraction ◽  
Experimental Studies ◽  
Test Substance ◽  
Organ Perfusion ◽  
Systemic Blood ◽  
Experimental Control ◽  
Arterial Blood ◽  
Vascular Connections

ABSTRACT Two techniques for organ perfusion with blood are described which provide a basis for exploring metabolic or endocrine dynamics. The technique of in situ perfusion with autogenous arterial blood is suitable for glands or small organs which receive a small fraction of the animal's cardiac output; thus, test stimulatory or inhibitory substances can be added to the perfusing blood and undergo sufficient dilution in systemic blood after passage through the perfused organ so that recirculation does not compromise experimental control over test substance concentration in the perfusate. Experimental studies with the in situ perfused adrenal are described. The second technique, termed the pilot organ method, is suitable for organs which receive a large fraction of the cardiac output, such as the liver. Vascular connections are made between the circulation of an intact, anaesthetized large (> 30 kg) dog and the liver of a small (< 3 kg) dog. The small dog's liver (pilot liver) is excised and floated in a bath of canine ascites, and its venous effluent is continuously returned to the large dog. Test substances are infused into either the hepatic artery or portal vein of the pilot liver, but the small size of the pilot liver and its blood flow in relation to the large dog minimize recirculation effects. A number of functional parameters of the pilot liver are described.

scholarly journals Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 27
Author(s):  
Jean-Paul Mosnier ◽  
Eugene T. Kennedy ◽  
Jean-Marc Bizau ◽  
Denis Cubaynes ◽  
Ségolène Guilbaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Rydberg Series ◽  
R Matrix ◽  
Resonance Strengths ◽  
Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

scholarly journals Saturation effects in SIDIS at very forward rapidities

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
E. Iancu ◽  
A. H. Mueller ◽  
D. N. Triantafyllopoulos ◽  
S. Y. Wei
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Virtual Photon ◽  
Large Fraction ◽  
Quark Distribution ◽  
High Energy ◽  
Longitudinal Momentum ◽  
Black Disk ◽  
Gluon Saturation

Abstract Using the dipole picture for electron-nucleus deep inelastic scattering at small Bjorken x, we study the effects of gluon saturation in the nuclear target on the cross-section for SIDIS (single inclusive hadron, or jet, production). We argue that the sensitivity of this process to gluon saturation can be enhanced by tagging on a hadron (or jet) which carries a large fraction z ≃ 1 of the longitudinal momentum of the virtual photon. This opens the possibility to study gluon saturation in relatively hard processes, where the virtuality Q2 is (much) larger than the target saturation momentum $$ {Q}_s^2 $$ Q s 2 , but such that z(1 − z)Q2 ≲ $$ {Q}_s^2 $$ Q s 2 . Working in the limit z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we predict new phenomena which would signal saturation in the SIDIS cross-section. For sufficiently low transverse momenta k⊥ ≪ Qs of the produced particle, the dominant contribution comes from elastic scattering in the black disk limit, which exposes the unintegrated quark distribution in the virtual photon. For larger momenta k⊥ ≳ Qs, inelastic collisions take the leading role. They explore gluon saturation via multiple scattering, leading to a Gaussian distribution in k⊥ centred around Qs. When z(1 − z)Q2 ≪ Q2, this results in a Cronin peak in the nuclear modification factor (the RpA ratio) at moderate values of x. With decreasing x, this peak is washed out by the high-energy evolution and replaced by nuclear suppression (RpA< 1) up to large momenta k⊥ ≫ Qs. Still for z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we also compute SIDIS cross-sections integrated over k⊥. We find that both elastic and inelastic scattering are controlled by the black disk limit, so they yield similar contributions, of zeroth order in the QCD coupling.

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