E. Takada

Doubly-resonant coherent excitation of HCI planar channeled in a Si crystal

We investigated resonant coherent excitation of H-like Ar17+ and He-like Ar16+ ions planar channeled in a Si crystal under the V-type and ladder-type double resonance conditions. In both cases, we observed distinct enhancement in the ionized fraction of the transmitted ions when the double resonance conditions were satis.ed. In the ladder-type configuration, the enhancement indicates that the doubly-excited 2p2 state of He-like Ar16+was produced through doubly-resonant coherent excitation.

Convoy electron emission following ionization of highly-charged ions excited by resonant coherent excitation

Projectile ionization of highly-charged Ar and Fe ions in the excited states passing relativistically fast through a thin crystalline foil was experimentally studied. We selectively controlled the population of the excited states of the projectiles, and their alignment by choosing a specific m-state through three-dimensional resonant coherent excitation technique by periodical electric fields in a crystalline. We measured energy-differential spectra of electron emission released from projectiles at zero degree. Under the resonance condition, we found an evident enhancement of the convoy electron yield, which reflects the electron momentum distribution of the initial bound state of the excited ions.

Electron emission from fast heavy ions associated with resonant coherent excitation

We observed convoy electrons emitted from 416 MeV/u He-like Ar16+ passing through a thin Si crystal under the condition of three-dimensional resonant coherent excitation (3D-RCE). The convoy electrons, which originate from electrons released from ions into the continuum by collisions with target atoms, emerged in the forward direction and formed a cusp-shaped peak in the energy distribution. We selectively controlled the population of the ground and excited states of ions traveling through the crystal by using 3D-RCE, where the 1s electron was excited to the 2p state by a periodic crystal field. Under the resonance condition, we found an enhancement of the convoy electrons with a narrowing in the energy distribution, which reflects the electron momentum distribution of the initial bound state of the excited ions.

A measurement of the π0 decay of Λ 12 C and Λ 11 B hypernucleihypernuclei@@@Иэмерения π0 распада гиперядер Λ 12 C и Λ 11 B

SummaryWe made a direct measurement of the π0 weak decay branching ratio of theΛ12C hypernucleus for the first time. The branching ratio is estimated to beΓπ0/Γ=0.166±0.055 from the measurement. The branching ratio agrees fairly with a theoretical calculation with a realistic pion distorted wave function, but is inconsistent with a calculation with a free π0 wave function. An upper limit of the π0 decay branching ratio of theΛ11B hypernucleus was also estimated to beΓπ0/Γ<0.291 (90% confidence level).RiassuntoÈ stata misurata direttamente la frazione di decadimento (debole) dell’ipernucleoΛ12C in π0 per la prima volta. Dalla misura risulta cheΓπ0/Γ=0.166±0.055. Il rapporto coincide con il calcolo teorico con una funzione d’onda distorta realistica pionica, ma non è in accordo con il calcolo con la funzione d’onda libera del pione. Anche il limite superiore stimato del rapporto di decadimento pionico dell’ipernucleoΛ11B èΓπ0/Γ<0.291 (livello di confidenza 90%).РеэюмеВпервые проводится прямое иэмерение отнощение ветвей π0 слабого распада гиперядерΛ12C. Иэ иэмерения оценивается отнощение ветвей, которое составляетΓπ0/Γ=0.166±0.055. Отнощение ветвей совпадает с теоретическим расчетом, испольэуюшим искаженную волновую функцию реального пиона, но не согласуется с вычислением для волновой функции свободного π0. Также оценивается верхний предел отнощения ветвей π0 распада гиперядраΛ11B, который составляетΓπ0/Γ<0.291 (с достоверностью 95%).