Measurement Of Branching Ratio Research Articles

The GRIFFIN data acquisition system

Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new experimental facility for radioactive decay studies at the TRIUMF-ISAC laboratory. This article describes the details of the custom designed GRIFFIN digital data acquisition system. The features of the system that will enable high-precision half-life and branching ratio measurements with levels of uncertainty better than 0.05% are described. The system has demonstrated the ability to effectively collect signals from High-purity germanium crystals at counting rates up to 50kHz while maintaining good energy resolution, detection efficiency and spectral quality.

In-beam study of 253No using the SAGE spectrometer

.The heavy actinide nucleus 253No (Z = 102) was studied using the (S)ilicon (A)nd (Ge)rmanium (SAGE) spectrometer allowing simultaneous in-beam gamma-ray and conversion electron spectroscopy at the accelerator laboratory of the University of Jyväskylä. Using the recoil-tagging technique, gamma-electron coincidences have allowed for the extension of the level scheme in the lower-spin region of the yrast band. In addition, internal conversion coefficient (ICC) measurements to establish the multipolarity of transitions have been performed. Measurement of the interband-intraband branching ratios supports the assignment of the Nilsson band-head configuration 9/2^{-}[734] assigned in previous studies. The study shows the viability of combined in-beam electron and gamma-ray spectroscopy down to μb cross sections.

Study of the rare decays

We investigate the effect of scalar leptoquarks and family non-universal bosons on the rare leptonic decays of mesons, mediated by the flavour-changing neutral-current transitions . They are sensitive to a variety of new physics operators as opposed to the leptonic modes and, hence, can provide an ideal testing ground to look for new physics beyond the Standard Model (SM). We work out the constraint on new physics parameter space using the measured branching ratios of processes and the mixing data. Using the constrained parameters we estimate the branching ratios of processes. We find that the branching ratios are reasonably enhanced from their corresponding SM values in the leptoquark model and are expected to be within the reach of Run II/III of Large Hadron Collider experiments.

Status of the CERN NA62 Experiment

The decay is one of the theoretically cleanest meson decays to look for indirect effects of new physics in a complementary way to direct searches at the LHC. The NA62 experiment at CERN SPS is designed to measure the branching ratio of this decay with 10% precision. NA62 is taking data since 2014, eventually reaching the final designed beam intensity. Using a sample of data taken in 2015, the experimental performances in view of the branching ratio measurement is reported.

Configurations and decay hindrances of high- K states in Hf180

Multi-quasiparticle high-K states, several of which are isomeric, were observed in Hf-180 with the Gammasphere array. We determined the lifetimes in the ns-μs range using centroid-shift and decay measurements within a mu s coincidence time window. The configurations of high-K states involve two and four quasiparticles, with states up to Kπ = (18-) established. High-K excitations are found to be progressively more favored with increasing excitation energy. The K quantum number is quite robust up to the highest spins observed, as evidenced by the large values of the reduced hindrance for isomeric decays. Furthermore, rotational bands built on three high-K states are identified, and the measured branching ratios in these sequences enable the assignment of underlying configurations. Multi-quasiparticle calculations using the Lipkin-Nogami approach for pairing, with blocking included, reproduce the observed high-K energies quite well.

Iterative precision measurement of branching ratios applied to 5P states in 88Sr+

We report and demonstrate a method for measuring the branching ratios of dipole transitions of trapped atomic ions by performing nested sequences of population inversions. This scheme is broadly applicable to species with metastable lambda systems and can be generalized to find the branching of any state to lowest states. It does not use ultrafast pulsed or narrow linewidth lasers and is insensitive to experimental variables such as laser and magnetic field noise as well as ion heating. To demonstrate its effectiveness, we make the most accurate measurements thus far of the branching ratios of both and states in 88Sr+ with sub-1% uncertainties. We measure 17.175(27) for the – branching ratio, 15.845(71) for –, and 0.056 09(21) for –. These values represent the first precision measurement for –, as well as ten- and thirty-fold improvements in precision respectively for – and – over the best previous experimental values.

Effects of Scalar Leptoquarks in b → s Transitions

We investigate the effect of scalar leptoquarks on the recent anomalies observed in rare semileptonic B meson decays involving the quark level transition b → s. The leptoquark parameter space is constrained by using the measured branching ratio of Bs → μ+μ- process. We estimate the branching ratios of B → K(*)μ+μ- (νν̅) processes, using the constrained leptoquark couplings. We also compute forward-backward asymmetry, polarization fractions of K* and P'5 observable in the B → K*μ+μ- process. The RK anomaly in the B → Kl+l- process is also studied. Furthermore, we predict the branching ratios of the lepton flavour violating decays, such as Bs→ li+lj-, B → K(*)li+lj- and Bs → ϕli+lj-, which are found to be within the experimental reach of LHCb and the upcoming Belle II experiments.

Shape coexistence from lifetime and branching-ratio measurements in 68,70Ni

Author(s): Crider, BP; Prokop, CJ; Liddick, SN; Al-Shudifat, M; Ayangeakaa, AD; Carpenter, MP; Carroll, JJ; Chen, J; Chiara, CJ; David, HM; Dombos, AC; Go, S; Grzywacz, R; Harker, J; Janssens, RVF; Larson, N; Lauritsen, T; Lewis, R; Quinn, SJ; Recchia, F; Spyrou, A; Suchyta, S; Walters, WB; Zhu, S | Abstract: Shape coexistence near closed-shell nuclei, whereby states associated with deformed shapes appear at relatively low excitation energy alongside spherical ones, is indicative of the rapid change in structure that can occur with the addition or removal of a few protons or neutrons. Near 68Ni (Z=28, N=40), the identification of shape coexistence hinges on hitherto undetermined transition rates to and from low-energy 0+ states. In 68,70Ni, new lifetimes and branching ratios have been measured. These data enable quantitative descriptions of the 0+ states through the deduced transition rates and serve as sensitive probes for characterizing their nuclear wave functions. The results are compared to, and consistent with, large-scale shell-model calculations which predict shape coexistence. With the firm identification of this phenomenon near 68Ni, shape coexistence is now observed in all currently accessible regions of the nuclear chart with closed proton shells and mid-shell neutrons.

Independent measurement of the Hoyle stateβfeeding fromB12using Gammasphere

Using an array of high-purity Compton-suppressed germanium detectors, we performed an independent measurement of the β-decay branching ratio from B12 to the second-excited state, also known as the Hoyle state, in C12. Our result is 0.64(11)%, which is a factor ∼2 smaller than the previously established literature value, but is in agreement with another recent measurement. This could indicate that the Hoyle state is more clustered than previously believed. The angular correlation of the Hoyle state γ cascade has also been measured for the first time. It is consistent with theoretical predictions.Received 12 January 2016DOI:https://doi.org/10.1103/PhysRevC.93.065803©2016 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeta decayCollective levelsElectromagnetic transitionsH & He burningNuclear astrophysicsNuclear reactionsNuclear structure & decaysProperties6 ≤ A ≤ 19Nuclear Physics

γ-Ray spectroscopy using a binned likelihood approach

The measurement of a reaction cross section from a pulse height spectrum is a ubiquitous problem in experimental nuclear physics. In γ-ray spectroscopy, this is accomplished frequently by measuring the intensity of full-energy primary transition peaks and correcting the intensities for experimental artifacts, such as detection efficiencies and angular correlations. Implicit in this procedure is the assumption that full-energy peaks do not overlap with any secondary peaks, escape peaks, or environmental backgrounds. However, for complex γ-ray cascades, this is often not the case. Furthermore, this technique is difficult to adapt for coincidence spectroscopy, where intensities depend not only on the detection efficiency, but also the detailed decay scheme. We present a method that incorporates the intensities of the entire spectrum (e.g., primary and secondary transition peaks, escape peaks, Compton continua, etc.) into a statistical model, where the transition intensities and branching ratios can be determined using Bayesian statistical inference. This new method provides an elegant solution to the difficulties associated with analyzing coincidence spectra. We describe it in detail and examine its efficacy in the analysis of 18O(p,γ)19F and 25Mg(p,γ)26Al resonance data. For the 18O(p,γ)19F reaction, the measured branching ratios improve upon the literature values, with a factor of 3 reduction in the uncertainties.

Higgs Boson Studies at the Tevatron

We present the combination of searches for the Standard Model Higgs boson at a center-of-mass energy of s=1.96 TeV, using the full Run 2 dataset collected with the CDF and D0 detectors at the Fermilab Tevatron collider. We also present combined measurements of Higgs Boson production cross sections, branching ratios, and couplings to fermions and bosons. Finally, we present tests of different spin and parity hypotheses for a particle H of mass 125 GeV produced in association with a vector boson and decaying into a pair of b quarks, and place constraints on such hypotheses using the D0 data.

Detection of protonated formaldehyde in the prestellar core L1689B

Complex organic molecules (COMs) are detected in many regions of the interstellar medium, including prestellar cores. However, their formation mechanisms in cold (~10 K) cores remain to this date poorly understood. The formyl radical HCO is an important candidate precursor for several O-bearing terrestrial COMs in cores, as an abundant building block of many of these molecules. Several chemical routes have been proposed to account for its formation: on grain surfaces, as an incompletely hydrogenated product of H addition to frozen-out CO molecules; and in the gas phase, either as the product of the reaction between H2CO and a radical or as a product of dissociative recombination of protonated formaldehyde H2COH+. The detection and abundance determination of H2COH+, if present, could provide clues as to whether this latter scenario might apply. We searched for protonated formaldehyde H2COH+ in the prestellar core L1689B using the IRAM 30 m telescope. The H2COH+ ion is unambiguously detected, for the first time, in a cold (~10 K) source. The derived abundance agrees with a scenario in which the formation of H2COH+ results from the protonation of formaldehyde. We use this abundance value to constrain the branching ratio of the dissociative recombination of H2COH+ towards the HCO channel to ~10−30%. This value could however be lower if HCO were efficiently formed from neutral-neutral reactions in the gas phase, and we stress the need for laboratory measurements of the rate constants of these reactions at 10 K. Given the experimental difficulties in measuring branching ratios experimentally, observations can place valuable constraints on these values and provide useful input for chemical networks.

Precision half-life measurement ofF17

Background: The precise determination of $ft$ values for superallowed mixed transitions between mirror nuclide are gaining attention as they could provide an avenue to test the theoretical corrections used to extract the ${V}_{ud}$ matrix element from superallowed pure Fermi transitions. The $^{17}\mathrm{F}$ decay is particularly interesting as it proceeds completely to the ground state of $^{17}\mathrm{O}$, removing the need for branching ratio measurements. The dominant uncertainty on the $ft$ value of the $^{17}\mathrm{F}$ mirror transition stems from a number of conflicting half-life measurements.Purpose: A precision half-life measurement of $^{17}\mathrm{F}$ was performed and compared to previous results.Methods: The life-time was determined from the \ensuremath{\beta} counting of implanted $^{17}\mathrm{F}$ on a Ta foil that was removed from the beam for counting. The $^{17}\mathrm{F}$ beam was produced by transfers reaction and separated by the TwinSol facility of the Nuclear Science Laboratory of the University of Notre Dame.Results: The measured value of ${t}_{1/2}^{\text{new}}=64.402\phantom{\rule{0.16em}{0ex}}$(42) s is in agreement with several past measurements and represents one of the most precise measurements to date. In anticipation of future measurements of the correlation parameters for the decay and using the new world average ${t}_{1/2}^{\text{world}}=64.398\phantom{\rule{0.16em}{0ex}}$(61) s, we present a new estimate of the mixing ratio $\ensuremath{\rho}$ for the mixed transition as well as the correlation parameters based on assuming Standard Model validity.Conclusions: The relative uncertainty on the new world average for the half-life is dominated by the large ${\ensuremath{\chi}}^{2}=31$ of the existing measurements. More precision measurements with different systematics are needed to remedy to the situation.

Study of the rare semileptonic decaysBd0→K*l+l−in scalar leptoquark model

We study the effect of scalar leptoquarks on the exclusive rare $B$ meson decays $\bar{B}_d^0 \rightarrow \bar{K}^{* 0}\left(\rightarrow K^-\pi^+\right) l^+ l^-$ in the full kinematically accessible physical region. We work out the constraints on leptoquark parameter space using the measured branching ratio of $B_s \rightarrow \mu^+ \mu^-$ process by the CMS and LHCb collaborations. We compute the branching ratio, forward-backward asymmetry and isospin asymmetry distribution using the constrained parameter space. We also look into various form factor independent and CP violating observables in the scalar leptoquark model.

Direct and indirect constraints on CP-violating Higgs-quark and Higgs-gluon interactions

We investigate direct and indirect constraints on the complete set of anomalous CP-violating Higgs couplings to quarks and gluons originating from dimension-6 operators, by studying their signatures at the LHC and in electric dipole moments (EDMs). We show that existing uncertainties in hadronic and nuclear matrix elements have a significant impact on the interpretation of EDM experiments, and we quantify the improvements needed to fully exploit the power of EDM searches. Currently, the best bounds on the anomalous CP-violating Higgs interactions come from a combination of EDM measurements and the data from LHC Run 1. We argue that Higgs production cross section and branching ratios measurements at the LHC Run 2 will not improve the constraints significantly. On the other hand, the bounds on the couplings scale roughly linearly with EDM limits, so that future theoretical and experimental EDM developments can have a major impact in pinning down interactions of the Higgs.

Improvements to TITAN’s mass measurement and decay spectroscopy capabilities

The study of nuclei farther from the valley of β-stability than ever before goes hand-in-hand with shorter-lived nuclei produced in smaller abundances than their less exotic counterparts. The measurement, to high precision, of nuclear masses therefore requires innovations in technique in order to keep up. TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN) facility deploys three ion traps, with a fourth in the commissioning phase, to perform and support Penning trap mass spectrometry and in-trap decay spectroscopy on some of the shortest-lived nuclei ever studied. We report on recent advances and updates to the TITAN facility since the 2012 EMIS conference.TITAN’s charge breeding capabilities have been improved and in-trap decay spectroscopy can be performed in TITAN’s Electron Beam Ion Trap (EBIT). Higher charge states can improve the precision of mass measurements, reduce the beam-time requirements for a given measurement, improve beam purity, and open the door to access isotopes not available from the ISOL method via in-trap decay and recapture. This was recently demonstrated during TITAN’s mass measurement of 30Al. The EBIT’s decay spectroscopy setup was commissioned with a successful branching ratio and half-life measurement of 124Cs. Charge breeding in the EBIT increases the energy spread of the ion bunch sent to the Penning trap for mass measurement, so a new Cooler PEnning Trap (CPET), which aims to cool highly charged ions with an electron plasma, is undergoing offline commissioning. Already CPET has demonstrated the trapping and self-cooling of a room-temperature electron plasma that was stored for several minutes. A new detector has been installed inside the CPET magnetic field which will allow for in-magnet charged particle detection.

Shape coexistence from lifetime and branching-ratio measurements in 68,70Ni

Shape coexistence from lifetime and branching-ratio measurements in 68,70Ni

Beta-delayed Neutron Emission: First Measurements in the Heavy Mass Region and Future Prospects

Beta-delayed neutrons play a key role in the formation of heavy elements in explosive stellar environments. The final r-process abundance distribution, including the rare-earth peak, is tailored to a large extent by the neutrons released after the beta decay of very exotic neutron-rich nuclei encountered along the r-process path and during the freeze-out phase. Such scenarios involve a vast amount of — yet undiscovered — nuclei, and most of them are expected to be neutron emitters. In this respect, existing beta-delayed neutron emission data is rather scarce, spanning from the lightest isotopes up to the region of the fission-fragments with masses up to A ∼ 150. This contribution gives an overview on the latest measurements of neutron branching ratios in the heavy mass region around N = 126, which was practically unexplored in the past. Present plans to access very exotic nuclei at the RIB-facility of RIKEN in the framework of the BRIKEN project, are presented, together with the expected impact in r-process nucleosynthesis studies.

Branching ratio measurements and isospin violation in B-meson decays

The approximate symmetry of the strong interactions under isospin transformations is among the most precise tools available to control hadronic matrix elements. It is crucial in extracting fundamental parameters, but also provides avenues for the search of phenomena beyond the Standard Model. The precision of the resulting predictions requires special care when determining the quantities they are to be tested with. Specifically, in the extraction of branching ratios often isospin symmetry is assumed at one point or another implicitly, implying a significant bias for precision analyses. We extract a bias-free value for the production asymmetry between charged and neutral B meson pairs at B factories and discuss its consequences for the determination of branching fractions generally, and isospin-violating observables like the rate asymmetries in B→J/ψK or B→K⁎γ decays specifically.

Towards an assessment of the ATLAS data on the branching ratioΓ(Λb0→ψ(2S)Λ0)/Γ(Λb0→J/ψΛ0)

Recently the ATLAS Collaboration at CERN reported on the measurement of the branching ratio R(Lambda_b) = Gamma(Lambda_b(0) -> psi(2S) Lambda(0))/Gamma(Lambda_b(0) -> J/psi Lambda(0)). The measured branching ratio R(Lambda_b) = 0.501 pm 0.033$ (stat) pm 0.019 (syst) was found to be lower than the covariant quark model prediction of R(Lambda_b) = 0.8 pm 0.1 calculated by us recently. We present a detailed analysis of the branching ratio R(Lambda_b) using a model-independent framework for the heavy-to-light form factors based on results from our previos papers.