Measurements of inelastic proton scattering with high energy resolution at forward scattering angles including
0
∘
are described. High-resolution halo-free beams were accelerated by the cyclotron ...complex at the Research Center for Nuclear Physics. Instrumental background events were minimized using the high-quality beam. The remaining instrumental background events were eliminated by applying a background subtraction method. As a result, clean spectra were obtained even for a heavy target nucleus such as
Pb
208
. A high energy resolution of 20
keV (FWHM) and a scattering angle resolution of
±
0
.
6
∘
were achieved at an incident proton energy of 295
MeV.
We report luminescence from spin triplet states of excitons bound to interstitial carbon-interstitial oxygen defects in silicon. The peak, which we call CT-line, has an energy 2.64meV lower than ...790meV (C-line), and splits into three peaks by application of magnetic field. Moreover, its peak position does not depend on the angle between the magnetic field direction and crystallographic orientation indicating the quenching of orbital angular momentum of the hole bound to the defect. These observations lead us to conclude that the CT-line is the photoluminescence from a triplet state.
We report the results of the experiments on dynamic nuclear polarization (DNP) of (29)Si nuclei under saturation the electron paramagnetic resonance (EPR) transitions of the photoexcited spin S=1 ...states of the oxygen+vacancy complexes in irradiated (29)Si isotopically controlled silicon. The effect of isotope (29)Si abundance on the line width and hyperfine structure of the Si-SL1 EPR spectra was observed. It was shown clearly that the decrease of the (29)Si abundance leads to the transformation the DNP mechanism from the "differential" to "resolved" solid-effect accompanied with the increase of DNP degree. High steady-state (29)Si nuclear polarization of 6% due to "resolved" solid-effect was achieved in silicon crystals with the (29)Si isotope abundance below 4.7%. It was found that the DNP induced by saturation the hyperfine structure EPR lines of triplet centers does not follow the symmetric first derivative EPR line shape, showing the additional contribution to the DNP process.
Intramolecular insertion of a C−C double bond into a C−C single bond was achieved by treatment of cyclobutanone bearing an o-styryl group at the 3-position with a catalytic amount of a cationic ...rhodium(I)-dppp complex. Initially, rhodium is inserted between the carbonyl carbon and the α-carbon of the cyclobutanone. Intramolecular coordination of the vinyl group results in its migratory insertion into the C−Rh linkage. Reductive elimination affords benzobicyclo3.2.1octan-3-one. Notably, a ring-opened α,β-unsaturated ketone was obtained when dppe was used instead of dppp. In this reaction, rhodium cleaved the bond between the α sp3 carbon and the β sp3 carbon of the cyclobutanone. The coordinating vinyl group directs this new regioselectivity of cleavage observed with the dppe ligand.
The magnetic field of three scaled-radial-sector fixed field alternating gradient (FFAG)-magnets has been measured. The magnets have very large horizontal (1 m) and vertical (0.3 m) apertures to ...store muons and achieve phase rotation in an FFAG ring. The measurements results are compared to a three-dimensional field analysis using the TOSCA code; the generated magnetic field agrees satisfactorily with the TOSCA calculation in a range of 0.5\% for a large transversal (x-y-z) area. The three magnets show satisfactory performance for use in a ten-sector ring for a high-brightness muon source.
PDF
