0000000001067401
AUTHOR
Pekka Pirinen
Shell-model study on event rates of lightest supersymmetric particles scattering off 83Kr and 125Te
We investigate the elastic and inelastic scattering of lightest supersymmetric particle (LSP) dark matter off two possible target nuclei, 83Kr and 125Te. For the nuclear-structure calculations, we employ the nuclear shell model using recently generated realistic interactions. We have condensed the nuclear-physics contribution to a set of nuclear-structure factors that are independent of the adopted supersymmetric (SUSY) model. Total event rates are then easily calculated by combining the nuclear-structure factors with SUSY parameters of choice. In particular, 125Te shows promise as a detector material with both the elastic and inelastic channels yielding an appreciable nuclear response. pee…
Systematic approach toβand2νββdecays of massA=100–136nuclei
In this work we perform a systematic study of pairs of single-$\ensuremath{\beta}$-decaying nuclei in the mass region $A=100--136$ to extract information on the effective value of the axial-vector coupling constant ${g}_{\mathrm{A}}$. As the many-body framework we use the quasiparticle random-phase approximation (QRPA) and its proton-neutron variant (pnQRPA) in single-particle valence bases with Woods-Saxon-calculated single-particle energies. It is found that, to a reasonable approximation, ${g}_{\mathrm{A}}$ is a linear function of the mass number $A$, with a slightly different parametrization below and above the mass $A=121$. Using the values of ${g}_{\mathrm{A}}$ extracted from the line…
Estimating the flux of the 14.4 keV solar axions
In this paper we present a calculation of the expected flux of the mono-energetic 14.4 keV solar axions emitted by the M1 type nuclear transition of $^{57}$Fe in the Sun. These axions can be detected, e.g., by inverse coherent Bragg-Primakoff conversion in single-crystal TeO$_2$ bolometers. The ingredients of this calculation are i) the axion nucleon coupling, estimated in several popular axion models and ii)the nuclear spin matrix elements involving realistic shell model calculations with both proton and neutron excitations. For the benefit of the experiments we have also calculated the branching ratio involving axion and photon emission
DigiPhysLab : kokeellista fysiikkaa kännykällä
Koronapandemia pakotti yliopistot ympäri maailman muuttamaan toimintatapojaan ja siirtymään etäopetukseen sukupolvelle ennennäkemättömässä laajuudessa. Erityisesti kokeellisen fysiikan kurssien osalta pakotettu etätyöskentely tuli useimmille fysiikan laitoksille puskista, eikä valmista toimivaa ratkaisua kokeellisen työskentelyn tekemiseen muualla kuin kampuksen laboratoriotilassa ollut. nonPeerReviewed
A framework for designing experimental tasks in contemporary physics lab courses
While lab courses are an integral part of studying physics aiming at a huge variety of learning objectives, research has shown that typical lab courses do not reach all the desired goals. While diverse approaches by lab instructors and researchers try to increase the effectiveness of lab courses, experimental tasks remain the core of any lab course. To keep an overview of these developments and to give instructors (and researchers) a guideline for their own professional efforts at hand, we introduce a research-informed framework for designing experimental tasks in contemporary physics lab courses. In addition, we demonstrate within the scope of the EU-co-funded DigiPhysLab-project how the f…
Inelastic WIMP-nucleus scattering to the first excited state in125Te
The direct detection of dark matter constituents, in particular the weakly interacting massive particles (WIMPs), is considered central to particle physics and cosmology. In this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. Examples considered previously were the first excited states of $^{127}$I and $^{129}$Xe and $^{83}$Kr. Here we examine $^{125}$Te, which offers some advantages and is currently being considered as a target.In all these cases the extra signature of the gamma rays following the de-excitation of these states has definite advantages over the purely nuclear recoil and, in principle, such a signat…
Solar neutrino detection in liquid xenon detectors via charged-current scattering to excited states
We investigate the prospects for real-time detection of solar neutrinos via the charged-current neutrino-nucleus scattering process in liquid xenon time projection chambers. We use a nuclear shell model, benchmarked with experimental data, to calculate the cross sections for populating specific excited states of the caesium nuclei produced by neutrino capture on $^{131}$Xe and $^{136}$Xe. The shell model is further used to compute the decay schemes of the low-lying $1^{+}$ excited states of $^{136}$Cs, for which there is sparse experimental data. We explore the possibility of tagging the characteristic de-excitation $\gamma$-rays/conversion electrons using two techniques: spatial separation…
Shell Model Description of Spin-Dependent Elastic and Inelastic WIMP Scattering off 119Sn and 121Sb
In this work, we calculate the spin structure functions for spin-dependent elastic and inelastic WIMP scattering off 119Sn and 121Sb. Estimates for detection rates are also given. 119Sn and 121Sb are amenable to nuclear structure calculations using the nuclear shell model (NSM). With the possible exception of 201Hg, they are the only such nuclei still unexplored theoretically for their potential of inelastic WIMP scattering to a very low excited state. The present calculations were conducted using a state-of-the-art WIMP–nucleus scattering formalism, and the available effective NSM two-body interactions describe the spectroscopic properties of these nuclei reasonably well. Structure functio…
DigiPhysLab : Digital Physics Laboratory Work for Distance Learning
Pursuing a broad range of learning objectives, effective physics laboratory courses need conducive-to-learning, motivating, and engaging experimental tasks. The Covid-19 pandemic has further increased the demand for quality experimental tasks which can also be used in online learning scenarios. The EU-funded DigiPhysLab-project meets this need by developing a set of 15 competence-centred experimental tasks which can be implemented by instructors effortlessly in their own lab courses, independent of whether they are held on-campus or in distance learning. For this, the project utilizes the broad availability of digital technologies like smartphones which allow an inexpensive data collection …
Charged-current neutrino-nucleus scattering off Xe isotopes
Xenon detectors are used in the search for dark matter and neutrinoless double-beta decay ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta})$. As the next-generation detectors reach masses in the ton scale, neutrinos from astrophysical sources are soon predicted to become background in such detectors. Theoretical predictions of neutrino scattering cross sections and information of nuclear structure effects therein are crucial in accounting for the background. We perform calculations for differential and total cross sections of charged-current neutrino scattering off the most abundant xenon isotopes. The nuclear-structure calculations are made in the proton-neutron quasiparticle random…
Neutral-Current Neutrino-Nucleus Scattering off Xe Isotopes
Large liquid xenon detectors aiming for dark matter direct detection will soon become viable tools also for investigating neutrino physics. Information on the effects of nuclear structure in neutrino-nucleus scattering can be important in distinguishing neutrino backgrounds in such detectors. We perform calculations for differential and total cross sections of neutral-current neutrino scattering off the most abundant xenon isotopes. The nuclear structure calculations are made in the nuclear shell model for elastic scattering, and also in the quasiparticle random-phase approximation (QRPA) and microscopic quasiparticle phonon model (MQPM) for both elastic and inelastic scattering. Using suit…
First microscopic evaluation of spin-dependent WIMP-nucleus scattering off 183W
We perform the first consistent calculation of elastic-scattering and inelastic-scattering structure functions for spin-dependent WIMP-nucleus scattering for 183W in a microscopic nuclear-theory framework. The nuclear structure calculations are performed in the microscopic interacting boson-fermion model (IBFM-2). Our results show that while 183W is very insensitive to spin-dependent elastic scattering, the structure function for inelastic scattering is quite sizable at small momentum transfers. Moreover, to our knowledge 183W provides the first studied case where inelastic scattering can compete with elastic scattering as the primary detection signal. peerReviewed
Theoretical direct WIMP detection rates for transitions to the first excited state inKr83
The direct detection of dark matter constituents, in particular the weakly interacting massive particles (WIMPs), is central to particle physics and cosmology. In this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. Examples considered previously were the first excited states of $^{127}\mathrm{I}$ and $^{129}\mathrm{Xe}$. We examine here $^{83}\mathrm{Kr}$, which offers some kinematical advantages and is a possible target. We estimate appreciable rates for the inelastic scattering mediated by the spin cross sections, with an inelastic event rate of $4.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ …
Shell-model study on event rates of lightest supersymmetric particles scattering offKr83andTe125
We investigate the elastic and inelastic scattering of lightest supersymmetric particle (LSP) dark matter off two possible target nuclei, $^{83}\mathrm{Kr}$ and $^{125}\mathrm{Te}$. For the nuclear-structure calculations, we employ the nuclear shell model using recently generated realistic interactions. We have condensed the nuclear-physics contribution to a set of nuclear-structure factors that are independent of the adopted supersymmetric (SUSY) model. Total event rates are then easily calculated by combining the nuclear-structure factors with SUSY parameters of choice. In particular, $^{125}\mathrm{Te}$ shows promise as a detector material with both the elastic and inelastic channels yie…
Effective axial-vector coupling in beta decay of mass region A = 100 - 134 isotopes
Tutkielmassa tarkastellaan massa-alueen A = 100 - 134 ytimien käyttäytymistä beetahajoamisessa käyttäen QRPA-formalismia. Tavoitteena oli tutkia heikon vuorovaikutuksen efektiivisen aksiaalivektorikytkentävakion gA käyttäytymistä massaluvun A funktiona. Tarkasteltavaksi valittiin kaikki mahdolliset ydintripletit, joissa on "keskellä" kaksoispariton (Z pariton, N pariton) ydin, jolla on 1+-perustila ja kokeellisesti havaittuja beetasiirtymiä kahden kaksoisparillisen naapuri-isobaarinsa kanssa. gA:n arvot kiinnitettiin laskemalla jokaisen kaksoisparittoman ytimen Gamow-Teller-matriisielementtien geometrinen keskiarvo ja sovittamalla se kokeelliseen dataan. Tuloksena saatiin lineaarinen malli …
Systematic approach to β and 2vββ decays of mass A=100-136 nuclei
In this work we perform a systematic study of pairs of single-β-decaying nuclei in the mass region A = 100–136 to extract information on the effective value of the axial-vector coupling constant gA. As the many-body framework we use the quasiparticle random-phase approximation (QRPA) and its proton-neutron variant (pnQRPA) in singleparticle valence bases with Woods-Saxon-calculated single-particle energies. It is found that, to a reasonable approximation, gA is a linear function of the mass number A, with a slightly different parametrization below and above the mass A = 121. Using the values of gA extracted from the linear fit, as well as an average constant value of gA, we calculate the tw…
Spin-dependent WIMP-nucleus scattering off 125Te, 129Xe, and 131Xe in the microscopic interacting boson-fermion model
We perform calculations of structure functions for elastic and inelastic spin-dependent scattering of weakly interacting massive particles (WIMPs) off 125Te, 129Xe, and 131Xe. The nuclear structure calculations are performed in the microscopic interacting boson-fermion model (IBFM-2). In our calculations we employ one-body and leading long-range two-body WIMP-nucleus currents derived from chiral effective field theory. We demonstrate that the relevant matrix elements can be reliably computed in the IBFM-2, which will allow investigation of heavy deformed nuclei previously inaccessible to theoretical calculations. peerReviewed
Economic and normative pressures as drivers for the adoption of International Accounting Standards in Finland since 1976
This paper deals with the internationalisation of Finnish business life and the attempts to introduce and apply international accounting standards (IASs) in Finnish accounting practice before the latest developments at the EU level in 2002. The internationalisation of business life creating economic pressures for changes is illustrated. Analysis of four accounting issues is made in order to exemplify how IASs have affected Finnish accounting legislation and practice. The results of the analysis indicate that the effect of IASs has been notable but secondary because of the implementation of the EU Directives in Finnish accounting legislation in the 1990s. IASs have not caused any drastic cha…