V. Lucherini

A New Measurement of Kaonic Hydrogen X-rays

The KN system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the K-series x rays of kaonic hydrogen atoms at the DANE electron-positron collider of Laboratori Nazionali di Frascati, and have de- termined the most precise values of the strong-interaction energy-level shift and width of the 1s atomic state. As x-ray detectors, we used large-area silicon drift detectors having excellent energy and timing resolution, which were developed especially for the SIDDHARTA experiment. The shift and width were determined to be ǫ1s = 283 ± 36(stat) ± 6(syst) eV and 1s = 541± 89(stat) ± 22(syst) eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy KN interaction.

Phenomenological statistical analysis of level densities, decay widths and lifetimes of excited nuclei

Abstract All existing data on the level densities, decay widths and lifetimes of excited nuclei have been analyzed in the framework of the statistical model in order to better determine the parameters of the phenomenological systematics of the nuclear level density. Data on level densities of several hundred nuclides obtained in the excitation energy range from 2 up to 20 MeV were used. The level densities of nuclei with large deformation (at the saddle point) have been studied by analyzing the data on the nuetron emission and fission partial width ratio Γn/Γf, and the values of the fission barrier heights Bf, the level density parameters ratio af/an and the saddle point shell corrections δWs.p. have been extracted. The influence of shell and collective effects on the level density and the decay widths of nuclei which have different excitation energies and deformations has been studied.

Kaonic hydrogen X-ray measurement in SIDDHARTA

Abstract Kaonic hydrogen atoms provide a unique laboratory to probe the kaon–nucleon strong interaction at the energy threshold, allowing an investigation of the interplay between spontaneous and explicit chiral symmetry breaking in low-energy QCD. The SIDDHARTA Collaboration has measured the K -series X rays of kaonic hydrogen atoms at the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati, and has determined the most precise values of the strong-interaction induced shift and width of the 1 s atomic energy level. This result provides vital constraints on the theoretical description of the low-energy K ¯ N interaction.

First measurement of the π+π- atom lifetime

The goal of the DIRAC experiment at CERN (PS212) is to measure the

Measurement of the total cross section for 238U photofission in the nucleon resonance region

\pi^+\pi^-

Absolute total photoabsorption cross sections on nuclei in the nucleon resonance region

atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the

DIRAC: A High Resolution Spectrometer for Pionium Detection

S

Quasi-elastic and inelastic inclusive electron scattering from an oxygen jet target

-wave

Determination of

\pi\pi

\pi\pi

scattering lengths combination