Measurement of energy spectra of charged particles emitted after the absorption of stopped negative pions in carbon

Energy spectra of charged particles (protons, deuterons, tritons, ³He, ⁴He and lithium nuclei) emitted after the absorption of stopped negative pions in a thin polyethylene target of 20 mg/cm² have been measured with high accuracy from the experimental threshold energy (of about 0.5 MeV) up to the kinematical limit of about 100 MeV.     

Composition of particles emitted at large PT and medium angles in pp collisions at s = 52.5 GeV

The relative yields of pions of both charges have been measured in the c.m angular 5.5° ?θ¹?21° in collisions at $\text{s=52.5}\text{GeV}$. The transverse momentum and x-dependence of these relative yields are presented and discussed.     

Spectroscopic study of 15N states with the reaction 14C(d,n)

Energy and angular distributions of neutrons from the reaction ¹⁴C(d, n)¹⁵N have been measured at 6.5 MeV deuteron energy. The DWBA analysis yielded l-values and absolute spectroscopic factors for fifteen states in ¹⁵N below 10 MeV excitation energy. For the 9.23 MeV level J^π is determined to be $\text{3}\text{2}$⁺ or $\text{5}\text{2}$⁺, for the 9.93 MeV level the data suggest $\text{J}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{+}}$. The spectroscopic factors are in qualitative agreement with pure jj coupling and in semi-quantitative agreement with shell-model calculations.     

Erzeugung neuer isomerer Kernzustände durch Kernphotoreaktionen am Antimon und Thallium

The systematic search for new short-lived isomeric states has been continued by irradiation of an additional 32 selected elements with 26 MeV bremsstrahlung. Isomeric transitions were detected using a conventional scintillation spectrometer. Irradiation of antimony led to the production of a new (530±50) μsec isomeric state which decays through emission of partially converted (62±2) keV and (76±3) keV gamma rays. The 530 μsec half-life is tentatively associated with the 136 keV level in Sb¹²². An apparent inconsistency in the previously proposed level scheme of Sb¹²² can be removed if the 3.5 min Sb¹²²-activity is assigned to an isomeric level in Sb¹²² lying less than 15 keV above the 136 keV isomeric state. A new measurement of the half-life of this level yielded a value of (4.1₅±0.2) min. Another new isomeric state with a (2.l±0.2) msec half-life was produced by irradiating thallium. The isomeric state decays by emission of two gamma rays of (335±8) keV and (597±12) keV which were found to be in coincidence. Irradiation of erbium led to the production of a short-lived isomeric transition which may be identical with a previously reported Ho-isomer. Results are discussed in the appendix.     

A Possible New Value for the Electron Mass from g-Factor Measurements on Hydrogen-Like Ions

The mass of the electron in atomic units (m _e) represents the largest error contribution in an experiment to determine the g-factor of the electron bound in hydrogen-like carbon. Recent progress in the calculation reduces the uncertainty of the theoretical value to such a low value that m _e can be determined from a comparison of experimental and theoretical g-factors. The present preliminary value of the electron mass agrees with the accepted value but reduces the uncertainty by about a factor 2. This revised version was published online in July 2006 with corrections to the Cover Date.     

X ray laser spectroscopy at the ESR: a proposed novel tool for the investigation of exotic isotopes

Novel X-ray laser sources driven by short-pulse high power lasers can provide intense beams of radiation at fixed energy. In combination with the Doppler-tuning possible at the ESR storage ring, this can be utilized for precision spectroscopy of highly charged ions. The sensitivity should be sufficient to apply this technique to lithium-like radioactive ions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Towards the determination of the charge radius of 11Li by laser spectroscopy

Isotope shift measurements by means of laser resonance ionization spectroscopy are a unique tool to determine the charge radii of halo nuclei. The most prominent halo nucleus ¹¹Li is at the same time the best accessible candidate for such studies. The experimental method to determine the charge radius of this exotic nucleus and first test results on ⁷Li will be presented in this paper. This revised version was published online in August 2006 with corrections to the Cover Date.     

Collimated-hole structures as efficient differential pumping barrier, one-way valve and tool for aligning Penning traps

A collimated-hole structure consists of a very large number of parallel channels which have each a very small diameter and are closely packed together. Such devices, installed in vacuum systems allow one to separate regions of very different gas pressures. A collimated-hole structure has high transmission for a directed ion beam with low emittance but a very low conductance for rest gas atoms or molecules exhibiting random walk. Therefore it is proposed to use such a structure as one-way valve and/or efficient differential pumping barrier in set-ups using Penning traps. Furthermore, these devices might be very useful to align the axis of a Penning trap with the direction of the magnetic field lines which is essential to avoid systematic uncertainties in high-accuracy mass spectroscopy.