Precision measurement of the branching fractions of the 4p 2P3/2 decay of Ca II (original) (raw)
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Precision Measurement Method for Branching Fractions of ExcitedP1/2States Applied toCa+40
Physical Review Letters, 2013
We present a method for measuring branching fractions for the decay of J = 1/2 atomic energy levels to lower-lying states based on time-resolved recording of the atom's fluorescence during a series of population transfers. We apply this method to measure the branching fractions for the decay of the 4 2 P 1/2 state of 40 Ca + to the 4 2 S 1/2 and 3 2 D 3/2 states to be 0.93565(7) and 0.06435(7), respectively. The measurement scheme requires that at least one of the lower-lying states be longlived. The method is insensitive to fluctuations in laser light intensity and magnetic field and is readily applicable to various atomic species due to its simplicity. Our result distinguishes well among existing state-of-the-art theoretical models of Ca + .
The need for branching fraction measurements in multiply-charged ions
Physica Scripta, 2007
Much progress has been made in the measurement of oscillator strengths in neutral and singly-ionized atoms, providing a database for use in important applications. However, for multiply-charged ions, measured data for oscillator strengths are almost exclusively limited to low-lying unbranched transitions. Although extensive measurements of ionic lifetimes exist, the lack of branching fraction measurements in multiply-charged ions prevents these data from being converted to oscillator strengths. A significant factor leading to this deficiency involves the lack of adequate line intensity calibration standards in the vacuum ultraviolet spectral region 2000-400 Å. Here we review the interrelationships connecting these rate parameters, indicate some of the important applications for which they are needed, describe the experimental limitations that currently exist, and suggest possible methods for extending these measurements below 1000 Å.
Measurement of the decay branching ratio
Physics Letters B, 2007
The reaction pd → 3 Heη at threshold was used to provide a clean source of η mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay η → π + π − e + e − is measured to be (4.3 ± 1.3 ± 0.4) × 10 −4 .
Experimental and theoretical study of the 3d^{2}D–level lifetimes of ^{40}Ca^{+}
Physical Review A, 2005
We report measurements of the lifetimes of the 3d D 5/2 and 3d 2 D 3/2 metastable states of a single laser-cooled 40 Ca + ion in a linear Paul trap. We introduce a new measurement technique based on high-efficiency quantum state detection after coherent excitation to the D 5/2 state or incoherent shelving in the D 3/2 state, and subsequent free, unperturbed spontaneous decay. The result for the natural lifetime of the D 5/2 state of 1168(9) ms agrees excellently with the most precise published value. The lifetime of the D 3/2 state is measured with a single ion for the first time and yields 1176(11) ms which improves the statistical uncertainty of previous results by a factor of four. We compare these experimental lifetimes to high-precision ab initio all order calculations and find a very good agreement. These calculations represent an excellent test of high-precision atomic theory and will serve as a benchmark for the study of parity nonconservation in Ba + which has similar atomic structure.
Measurements of relative branching ratios of Λc+ decays into states containing Σ
Physics Letters B, 2002
We have studied the Cabibbo suppressed decay Λ + c → Σ + K * 0 (892) and the Cabibbo favored decays Λ + c → Σ + K + K − , Λ + c → Σ + φ and Λ + c → Ξ * 0 (Σ + K − )K + and measured their branching ratios relative to Λ + c → Σ + π + π − to be (7.8 ± 1.8 ± 1.3)%, (7.1 ± 1.1 ± 1.1)%, (8.7 ± 1.6 ± 0.6)% and (2.2 ± 0.6 ± 0.6)%, respectively. The first error is statistical and the second is systematic. We also report two 90% confidence level limits Γ(Λ + c → Σ − K + π + )/Γ(Λ + c → Σ + K * 0 (892)) < 35% and Γ(Λ + c → Σ + K + K − ) N R /Γ(Λ + c → Σ + π + π − ) < 2.8%.
Measurementof the 4s(2) S-1(0) -> 4s3d D-1(2) transition probability in calcium
We have measured the ratio between the transition probabilities of two forbidden lines in Ca: the intercombination line at 657.3 nm and the E2 line at 457.5 nm. The value we obtained for this ratio is (54.1 ± 2.4). Combined with the most accurate value available in literature for the lifetime of the 3 P1 level, our measurement gives a value of (54.4 ± 4.0) s −1 for the 1 S0 → 1 D2 transition probability, significantly more accurate than the previous determinations.
The European Physical Journal D - Atomic, Molecular and Optical Physics, 2003
We have measured the ratio between the transition probabilities of two forbidden lines in Ca: the intercombination line at 657.3 nm and the E2 line at 457.5 nm. The value we obtained for this ratio is (54.1 ± 2.4). Combined with the most accurate value available in literature for the lifetime of the 3 P1 level, our measurement gives a value of (54.4 ± 4.0) s −1 for the 1 S0 → 1 D2 transition probability, significantly more accurate than the previous determinations.
The open LPC Paul trap for precision measurements in beta decay
The European Physical Journal A, 2019
The LPCTrap experiment uses an open Paul trap which was built to enable precision measurements in the beta decay of radioactive ions. The initial goal was the precise measurement of the beta-neutrino angular correlation coefficient in the decay of 6 He. Its geometry results from a careful optimization of the harmonic potential created by cylindrical electrodes. It supersedes previously considered geometries that presented a smaller detection solid angle to the beta particle and the recoiling ion. We describe here the methods which were used for the potential optimization, and we present the measured performances in terms of trapping time, cloud size and temperature, and space charge related limits. The properties of the ion cloud at equilibrium are investigated by a simple numerical simulation using hard sphere collisions, which additionally gives insights on the trapping loss mechanism. The interpretation for the observed trapping lifetimes is further corroborated by a model recently developed for ion clouds in Paul traps. The open trap shall serve other projects. It is currently used for commissioning purpose in the TRAPSENSOR experiment and is also considered in tests of the Standard Model involving the beta decay of polarized 23 Mg and 39 Ca ion in the frame of the MORA experiment. The latter tests require in-trap polarization of the ions and further optimization of the trapping and detection setup. Based on the results of the simulations and of their interpretation, different improvements of the trapping setup are discussed.