Abundance of Delta Resonances in 58Ni+58Ni Collisions between 1 and 2 AGeV

Charged pion spectra measured in 58Ni-58Ni collisions at 1.06, 1.45 and 1.93 AGeV are interpreted in terms of a thermal model including the decay of Delta resonances. The transverse momentum spectra of pions are well reproduced by adding the pions originating from the Delta-resonance decay to the component of thermal pions, deduced from the high transverse momentum part of the pion spectra. About 10 and 18% of the nucleons are excited to Delta states at freeze-out for beam energies of 1 and 2 AGeV, respectively.Comment: 14 pages, LaTeX with 3 included figures; submitted to Physics Letters

Stopping and Radial Flow in Central 58Ni + 58Ni Collisions between 1 and 2 AGeV

The production of charged pions, protons and deuterons has been studied in central collisions of 58Ni on 58Ni at incident beam energies of 1.06, 1.45 and 1.93 AGeV. The dependence of transverse-momentum and rapidity spectra on the beam energy and on the centrality of the collison is presented. It is shown that the scaling of the mean rapidity shift of protons established for AGS and SPS energies is valid down to 1 AGeV. The degree of nuclear stopping is discussed; the IQMD transport model reproduces the measured proton rapidity spectra for the most central events reasonably well, but does not show any sensitivity between the soft and the hard equation of state (EoS). A radial flow analysis, using the midrapidity transverse-momentum spectra, delivers freeze-out temperatures T and radial flow velocities beta_r which increase with beam energy up to 2 AGeV; in comparison to existing data of Au on Au over a large range of energies only beta_r shows a system size dependence

℮-conome: an automated tissue counting platform of cone photoreceptors for rodent models of retinitis pigmentosa

<p>Abstract</p> <p>Background</p> <p>Retinitis pigmentosa is characterized by the sequential loss of rod and cone photoreceptors. The preservation of cones would prevent blindness due to their essential role in human vision. Rod-derived Cone Viability Factor is a thioredoxin-like protein that is secreted by rods and is involved in cone survival. To validate the activity of Rod-derived Cone Viability Factors (RdCVFs) as therapeutic agents for treating retinitis Pigmentosa, we have developed e-conome, an automated cell counting platform for retinal flat mounts of rodent models of cone degeneration. This automated quantification method allows for faster data analysis thereby accelerating translational research.</p> <p>Methods</p> <p>An inverted fluorescent microscope, motorized and coupled to a CCD camera records images of cones labeled with fluorescent peanut agglutinin lectin on flat-mounted retinas. In an average of 300 fields per retina, nine Z-planes at magnification X40 are acquired after two-stage autofocus individually for each field. The projection of the stack of 9 images is subject to a threshold, filtered to exclude aberrant images based on preset variables. The cones are identified by treating the resulting image using 13 variables empirically determined. The cone density is calculated over the 300 fields.</p> <p>Results</p> <p>The method was validated by comparison to the conventional stereological counting. The decrease in cone density in <it>rd1 </it>mouse was found to be equivalent to the decrease determined by stereological counting. We also studied the spatiotemporal pattern of the degeneration of cones in the <it>rd1 </it>mouse and show that while the reduction in cone density starts in the central part of the retina, cone degeneration progresses at the same speed over the whole retinal surface. We finally show that for mice with an inactivation of the Nucleoredoxin-like genes <it>Nxnl1 </it>or <it>Nxnl2 </it>encoding RdCVFs, the loss of cones is more pronounced in the ventral retina.</p> <p>Conclusion</p> <p>The automated platform ℮-conome used here for retinal disease is a tool that can broadly accelerate translational research for neurodegenerative diseases.</p

Charged pions from Ni on Ni collisions between 1 and 2 AGeV

Charged pions from Ni + Ni reactions at 1.05, 1.45 and 1.93 AGeV are measured with the FOPI detector. The mean $\pi^{\pm}$ multiplicities per mean number of participants increase with beam energy, in accordance with earlier studies of the Ar + KCl and La + La systems. The pion kinetic energy spectra have concave shape and are fitted by the superposition of two Boltzmann distributions with different temperatures. These apparent temperatures depend only weakly on bombarding energy. The pion angular distributions show a forward/backward enhancement at all energies, but not the $\Theta = 90^0$ enhancement which was observed in case of the Au + Au system. These features also determine the rapidity distributions which are therefore in disagreement with the hypothesis of one thermal source. The importance of the Coulomb interaction and of the pion rescattering by spectator matter in producing these phenomena is discussed

Central Collisions of Au on Au at 150, 250 and 400 A MeV

Collisions of Au on Au at incident energies of 150, 250 and 400 A MeV were studied with the FOPI-facility at GSI Darmstadt. Nuclear charge (Z < 16) and velocity of the products were detected with full azimuthal acceptance at laboratory angles of 1-30 degrees. Isotope separated light charged particles were measured with movable multiple telescopes in an angular range of 6-90 degrees. Central collisions representing about 1 % of the reaction cross section were selected by requiring high total transverse energy, but vanishing sideflow. The velocity space distributions and yields of the emitted fragments are reported. The data are analysed in terms of a thermal model including radial flow. A comparison with predictions of the Quantum Molecular Model is presented.Comment: LateX text 62 pages, plus six Postscript files with a total of 34 figures, accepted by Nucl.Phys.

Entropy production in the Au + Au reaction between 150 and 800 A MeV

The entropy per nucleon (S/A) has been extracted for the Au [(150—800)A MeV] + Au reaction by using the phase I setup of the 4 pi facility at GSI, Darmstadt. The entropy has been obtained from the comparison of various observables characterizing the dM/dZ fragment multiplicity distributions, extending up to Z~15, with those calculated with the quantum statistical model. It is the first time that S/A values are determined by considering the full ensemble of charged products detected in the reaction. Consistent values of S/A are found from different methods. These entropy values are shown to be fairly independent of the volume of the ``participant'' region considered. They are somewhat lower than those extracted in earlier works but are in good agreement with hydrodynamic calculations and suggest a low viscosity for the hot and dense nuclear matter

ÉTUDE DE RÉACTIONS NUCLÉAIRES AVEC UN SPECTROGRAPHE MAGNÉTIQUE

Des réactions nucléaires induites par des deutérons sur des cibles d'adénine ainsi que des réactions nucléaires induites par 3He sur des cibles de 12C, 13C et 14C ont été étudiées au spectrographe magnétique à large bande, type Buechner.Nuclear reactions induced by deuterons on adenine targets and nuclear reactions induced by He3 on C12, C13 and C14 targets have been studied with a Buechner-type magnetic spectrograph

Distributions angulaires de protons et corrélation angulaire p-γ dans la réaction 11B(d, p)12B

Measurement at Ed = 5.5 Me V of the angular distribution of protons from the reaction 11B(d, p)12B going respectively to the ground state and the first and second excited states confirms the values ln = 1,1 and 0 found by other authors. The parities of these levels are therefore respectively +, + and —. Analysis of the p-γ angular correlation in the d-p plane for the first excited level (0.95 MeV) of 12B allows the exclusion of the value J = 0 for the angular momentum of this level. The only possibilities are J = 1 + or 2+ with a mixture of multipolarities for the 0.95 MeV gamma transition, or J = 3+ with pure E2 radiation.La mesure à Ed = 5,5 MeV de la distribution angulaire des protons allant respectivement au niveau fondamental, aux premier et deuxième niveaux excités de 12 B dans la réaction 11B(d, p)12B confirme les valeurs ln = 1,1 et 0 trouvées par d'autres auteurs. Les parités de ces niveaux sont donc respectivement +, + et —. L'analyse de la corrélation angulaire p-γ, dans le plan d-p par le premier niveau excité (0,95 MeV) de 12B, permet d'exclure la valeur J = 0 pour le moment angulaire de ce niveau. Les seules possibilités sont soit J =1 + ou 2+ avec mélange de multipolarité pour le rayonnement γ de 0,95 MeV, soit J = 3+ (E2 pur)

Courbes d'excitation de certains rayonnements γ dans la réaction 12C(d, p) 13C

Intensities of de-excitation gamma rays to the ground state from the first three levels of 13C, in the reaction 12C(d, p) 13C, were measured between Ed = 1.2 and 4.3 MeV. Excitation curves of the corresponding proton groups p1, p2 and p3 were deduced. The experimental results have been compared with the relative intensities calculated from the penetrability factors for different values of the orbital angular momentum of the protons in the reaction 13C + p. This has made it possible to obtain information about the spins and parities of levels at 11.76; 12.41; 12. 61 and 12.94 MeV in 14N.Les intensités des rayonnements γ de désexcitation des trois premiers niveaux excités de 13C vers le niveau fondamental ont été mesurées dans la réaction 12C(d, p)13C entre Ed = 1,2 et 4,3 MeV. On en a déduit les courbes d'excitation des groupes de protons p1, p2 et p3 correspondants. Les résultats expérimentaux ont été comparés aux intensités relatives calculées à l'aide des facteurs de pénétrabilité pour différentes valeurs du moment orbital des protons dans la réaction 13C + p, ce qui a permis de donner des précisions sur les spins et parités des niveaux de 11,76 ; 12,41 ; 12,61 et 12,94 MeV de 14N