A passive neutron dosemeter for measurements in mixed neutron-photon radiation fields

The project combines the highly sensitive salt(NaCl) dosemeter for photon radiation with a neutronphotonconverter in the form of thin gadolinium foilsenclosing the salt. Using an identical salt dosemeter butwithout gadolinium cover determines the primaryphoton contribution. With these twin dosemeters placedin a polyethylene sphere, both photon and neutron dosecontributions can be estimated. This paper describes thedesign and optimization of the construction as well astests and a preliminary calibration of the dosemeter forestimation of neutron dose equivalent in the mixedneutron and photon beam from a Cf-252 source.Currently, the lowest neutron dose equivalent possibleto quantify is around 1 mSv. Some suggestions forfurther improvements are also discussed

Meeting global temperature targets-the role of bioenergy with carbon capture and storage

In order to meet stringent temperature targets, active removal of CO2 from the atmosphere may be required in the long run. Such negative emissions can be materialized when well-performing bioenergy systems are combined with carbon capture and storage (BECCS). Here, we develop an integrated global energy system and climate model to evaluate the role of BECCS in reaching ambitious temperature targets. We present emission, concentration and temperature pathways towards 1.5 and 2 degrees C targets. Our model results demonstrate that BECCS makes it feasible to reach temperature targets that are otherwise out of reach, provided that a temporary overshoot of the target is accepted. Additionally, stringent temperature targets can be met at considerably lower cost if BECCS is available. However, the economic benefit of BECCS nearly vanishes if an overshoot of the temperature target is not allowed. Finally, the least-cost emission pathway over the next 50 years towards a 1.5 degrees C overshoot target with BECCS is almost identical to a pathway leading to a 2 degrees C ceiling target

Variation in gamma dose rate in different locations following the Chernobyl accident

Radionuclides from the Chernobyl accident were released and dispersed during a limited period of time, but under different weather conditions. As a result the radionuclides were unevenly distributed on the ground. During the years the initial deposition has been altered at some locations by different processes, but remains relatively unchanged in others. Here we report on the current inhomogeneous radionuclide distribution, on both large- and small scales (1 cm2 – 10ths of km2), which on average varies a factor of 4

Implementationsintentioner som strategi för emotionsreglering av spindelrädsla

Even though intentions works as predictors for behavior, research has shown a weak relation between the two. Implementation intentions has been shown to be effective in bridging the gap between intention and behavior, under various circumstances, for example when it comes to emotion regulation. Implementation intentions are ”If... then”-plans that connect a situation to a desired behavior. This study examined implementation intentions effectiveness in regulating fear in spider fearful participants when presented with spider stimuli, with an increasing grade of strain. The study partially replicated Schweiger Gallo et al.:s (2009) study, and extended it by having longer duration of picture-exposure, showing a video and also a casted spider skin. A behavior measure was added to the spider skin condition. The changes were intended to increase the ecological validity of the study and to test implementation intentions under more strenuous circumstances than before studied in emotion regulation. The results supported implementation intentions effectiveness in helping to induce behaviors that are congruent with intentions, when it came to measures with behavior. No differences between the groups were found for self-report measures in any of the conditions. Contrary to the hypothesis, mere goal intentions were found to be more effective in regulating arousal during exposure to the video.Även om intentionen att agera fungerar som prediktor till beteende så har den samlade forskningen visat på en svaghet i intentioners kraft att påverka beteenden. Implementationsintentioner har visat sig effektiva för att skapa beteenden i kongruens med intentioner under en rad omständigheter, bland annat för reglering av emotioner. Implementationsintentioner är påståenden i ”Om ... då”- form som binder en situation till ett önskat beteende. Denna studie undersökte implementationsintentioners effektivitet för reglering av emotionen rädsla hos spindelrädda personer, inför spindelstimuli med stegrande grad av påfrestning. Studien replikerade delvis en studie av Schweiger Gallo et al. (2009) och utökade den genom längre exponeringstid på bilderna, visning av en video samt visning av ett ömsat spindelskal. Ett beteendemått lades till vid spindelskalsvisning. Dessa förändringar var ämnade att öka den ekologiska validiteten och testade implementationsintentioner under mer krävande omständigheter än vad som tidigare har gjorts för emotionsreglering. Resultaten gav stöd för implementationsintentioners effektivitet för att skapa beteenden i kongruens med intentioner när det gällde beteendemått. Däremot observerades inga skillnader mellan grupperna för självskattning i någon av betingelserna, samt en motsatt förväntad effekt för arousal under videovisningen, där målintentioner visade sig mer effektiva

Region-specific radioecological evaluation of accidental releases of radionuclides from ESS

Gadolinium-148 is one of the radionuclides of most concern that will be produced in the tungsten target of the European Spallation Source (ESS), as a by-product of the spallation reaction used by the facility to produce neutrons. Since 148Gd a pure alpha emitter, it is both very radiotoxic and difficult to measure. With its half-life of 75 years, it will remain in the environment for a long time if released from the facility during normal operation or after an accident. There are still uncertainties regarding the amounts that actually will be produced by spallation in the tungsten targets of the facility. As Gd-148 does not occur naturally in the environment, there is no information available about its analysis in environmental samples but a few studies provide data from irradiated target material analysed by alpha spectroscopy or inductively coupled plasma mass spectrometry (ICP-MS). This report is a continuation of the SSM project as described in the SSM report 2020:08, entitled “Identifying radiologically important ESS-specific radionuclides and relevant detection methods” that focused on the ESS-related radionuclides that will be the most relevant to study and monitor in the environment as well as the analytical techniques to detect them. The present report focuses on the rare earth elements (REEs), including their radioactive isotopes, in particular Gd-148, and is intended to highlight the knowledge gaps that exist regarding their fate in the specific environment of the ESS area. In the first part of the report, the available literature on radioecological models was reviewed, with emphasis on ESS-related radionuclides. The existing modelling programmes were surveyed as well as the most relevant environmental parameters and experimental radioecological data required to build models specific to the ESS.In the second part of the report, the area in the vicinity of the ESS was surveyed to identify the important producers of foodstuff, what plant species are grown in the area and also the local husbandry and hunting practices, in order to identify critical pathways after a radioactive dispersion into the environment in connection with a potential accident at the ESS. In the third part of this report, after a thorough literature review and preliminary assays, we propose to investigate the use of ICP-MS for assessment of Gd-148 in the event of an accidental release, knowing that this analytical technique is already used for the measurement of stable Gd and REEs in the environment. The existing methods to extract REEs from environmental samples (soil, water, plants, and animal products) and to properly assess their concentration are described in the form of a literature review. The presented examples of methods were selected to fit the type of environment found around the ESS facility and the local agricultural and horticultural practices. A pilot study was also conducted to test extraction and measurement methods on the specific type of soil around ESS. These results are presented at the end of this report

Evaluation of the region-specific risks of accidental radioactive releases from the European Spallation Source

The European Spallation Source (ESS) is a neutron research facility under construction in southern Sweden. The facility will produce a wide range ofradionuclides that could be released into the environment. Some radionuclides are of particular concern such as the rare earth gadolinium-148. In this article, the local environment was investigated in terms of food production and rare earth element concentration in soil. The collected data will later be used to model thetransfer of radioactive contaminations from the ESS

Uncertainty Analysis and Order-by-Order Optimization of Chiral Nuclear Interactions

Chiral effective field theory (chi EFT) provides a systematic approach to describe low-energy nuclear forces. Moreover, chi EFT is able to provide well-founded estimates of statistical and systematic uncertainties-although this unique advantage has not yet been fully exploited. We fill this gap by performing an optimization and statistical analysis of all the low-energy constants (LECs) up to next-to-next-to-leading order. Our optimization protocol corresponds to a simultaneous fit to scattering and bound-state observables in the pion-nucleon, nucleon-nucleon, and few-nucleon sectors, thereby utilizing the full model capabilities of chi EFT. Finally, we study the effect on other observables by demonstrating forward-error-propagation methods that can easily be adopted by future works. We employ mathematical optimization and implement automatic differentiation to attain efficient and machine-precise first-and second-order derivatives of the objective function with respect to the LECs. This is also vital for the regression analysis. We use power-counting arguments to estimate the systematic uncertainty that is inherent to chi EFT, and we construct chiral interactions at different orders with quantified uncertainties. Statistical error propagation is compared with Monte Carlo sampling, showing that statistical errors are, in general, small compared to systematic ones. In conclusion, we find that a simultaneous fit to different sets of data is critical to (i) identify the optimal set of LECs, (ii) capture all relevant correlations, (iii) reduce the statistical uncertainty, and (iv) attain order-by-order convergence in chi EFT. Furthermore, certain systematic uncertainties in the few-nucleon sector are shown to get substantially magnified in the many-body sector, in particular when varying the cutoff in the chiral potentials. The methodology and results presented in this paper open a new frontier for uncertainty quantification in ab initio nuclear theory