Simulation tool development and sensitivity analysis of 160Gd double beta decay search by the PIKACHU project

147Nd quantification using HSCCC-purified samples.

The search for neutrinoless double beta decay (0νββ) is fundamental for investigating lepton-number violation, probing new physics beyond the Standard Model, and determining whether neutrinos are Majorana particles. CUORE (Cryogenic Underground Observatory of Rare Events), a cryogenic bolometric experiment at LNGS, studies 0νββ in 130Te using 988 TeO2 crystals. It is a milestone of cryogenic detector arrays with a tonne-scale detector operated for more than 7 years below 15 mK. Since 2017, CUORE has accumulated over 2.9 tonne-years of exposure. Thanks to a detailed background reconstruction across a broad energy range, CUORE has achieved one of the leading 0νββ limits and one of the most precise two-neutrino double beta decay (2νββ) half-life measurements. Building on CUORE's success, CUPID (CUORE Upgrade with Particle ID) aims to significantly enhance its 0νββ discovery sensitivity to 1027 yr in 100Mo, covering the Inverted Hierarchy of neutrino masses. It will employ lithium molybdate (Li2MoO4) crystals enriched in 100Mo, alongside germanium light detectors with Neganov-Trofimov-Luke amplification. The simultaneous readout of heat and light will benefit to enhance background rejection, particularly against alpha contamination and 2νββ pileup.CUPID will reuse CUORE's cryostat and infrastructure. Current efforts focus on detector performance validation, sensitivity studies, and finalizing the experimental design to maximize physics reach. This work presents the latest CUORE results and outlines the key milestones toward CUPID's realization.

Objective.Clustered pinhole (CP) collimation currently supports sub-millimeter resolution imaging up to ∼1 MeV, enabling SPECT of alpha and beta emitters with gamma emissions, simultaneous multi-isotope PET and PET/SPECT, and positron range-free PET. Nonetheless, increasing sensitivity in the original CP designs by enlarging pinhole diameters is limited, as the resulting pinhole opening cones would overlap.Approach. To address this limitation, the use of Super-Cluster (SC) collimation was evaluated in a simulation study. Two SC designs were assessed: a standard configuration (SC-ST) offering a resolution-sensitivity trade-off similar to CP, and a high-sensitivity variant (SC-HS) with larger pinhole diameters to enhance sensitivity. Their performance was compared to CP collimation for18F at concentrations of 1.0, 0.1, 0.05 MBq ml-1and ⁸⁹Zr at 2.0, 0.2, 0.1 MBq ml-1, evaluating sensitivity, image resolution, recovery coefficients, and uniformity.Main results.CP and SC-ST showed comparable sensitivity and image resolution. Both resolved18F rods of 0.9, 1.4, and 1.8 mm at 1.0, 0.1, and 0.05 MBq ml-1, respectively. For ⁸⁹Zr, rods down to 1.0 mm and 1.6 mm were resolved at 2.0 and 0.2 MBq ml-1, but none at 0.1 MBq ml-1. Compared to CP and SC-ST, SC-HS increased sensitivity threefold for18F and twofold for ⁸⁹Zr. At the highest activity, SC-HS showed slightly reduced resolution for18F (1.0 mm) and similar for ⁸⁹Zr (1.0 mm). However, it clearly outperformed both other collimators at lower activities, resolving18F rods of 1.2 and 1.4 mm at 0.1 and 0.05 MBq ml-1, respectively, and ⁸⁹Zr rods of 1.4 and 1.6 mm at 0.2 and 0.1 MBq ml-1. Additionally, SC-HS showed superior contrast recovery. Image uniformity remained consistent across all collimators, confirming effective angular sampling.Significance.The new SC geometry enables high-sensitivity collimation for high gamma energies, improving image quality at low activities. These results demonstrate SC collimation's strong potential for sensitivity-critical applications.

New measurements of the β decay of Ga 64 and Ga 66 have been carried out using total absorption spectroscopy at CERN-ISOLDE. The purpose of the study was to determine whether systemic effects such as have affected previous measurements and also determine the degree of isospin mixing in these proton-rich nuclei. Our results show that the β strength distribution of Ga 64 was previously underestimated, while that of Ga 66 agrees well with previous high-resolution measurements. The results allowed us to determine the amount of isospin mixing in the 0 + → 0 + transitions to the ground states of the daughter nuclei. From the extracted log f t values, we determined the isospin mixing parameter α for the two cases. They were found to be consistent with values for similar transitions in other nuclei. Ga 64 exhibits the largest amount of isospin mixing in such nuclei. These findings improve our understanding of beta decay and have implications for nuclear structure models and medical applications of Ga 66 in PET imaging.

Abstract The characteristic rapid rise and decline at optical wavelengths of a kilonova is the product of the low ejecta mass (≲0.05 M ⊙ ) and high ejecta velocity (≳0.1 c ). We show that, even at very early times (≲2 days), regions of ejecta fall below critical density and temperature thresholds at which nonlocal thermodynamic equilibrium (NLTE) effects become important. Here, we present an approximate method for calculating the ionization state of the ejecta that accounts for the NLTE impact of high-energy electrons produced in the beta decay of freshly synthesized r -process elements. We find that incorporating ionization from high-energy electrons produces an “inverted” and “blended” ionization structure, where the most highly ionized species are located in the fastest moving homologous ejecta, and multiple ionization states coexist. In radiation transport calculations, the higher degree of ionization reduces line blanketing in optical bands, leading to improved agreement with the light-curve properties of AT 2017gfo, such as the duration, decay rates, brightness, and colors. Our quasi-NLTE implementation helps to alleviate tensions in kilonova modeling: for high-velocity (∼0.3 c ) ejecta components, our models require less mass for a given peak brightness in optical bands, by as much as a factor of 3; our models can explain the presence of observed features associated to Sr II , W III , Se III , and Te III under conditions where LTE models would predict only neutral species; and we naturally predict the coexistence of species like Sr II and Ce III without the need for fine-tuning of the ejecta properties.

Details of the two-loop analysis of long-distance QED radiative corrections to neutron beta decay are presented. Explicit expressions are given for hard, jet, and soft functions appearing in the factorization formula that describes the limit of small electron mass and large electron energy. Numerical enhancements from the infrared region are resummed using renormalization group methods. Power corrections, cancellation of singularities in the small-mass expansion, renormalization scheme dependence, and bound-state effects are also discussed. These results provide the most precise determination of long-distance radiative corrections to neutron beta decay and impact the determination of | V u d | from the measured neutron lifetime and thus set a target for uncertainty reductions in the experimental and short-distance inputs.

The properties of neutron excess germanium nuclei are predicted utilizing a single particle model. The single particle model calculations include alpha, beta, positron, electron capture, and spontaneous fission decay modes. Neutron emission decay modes that have short half-lives are not readily determined by the model. However, estimates of the neutron decay mode were evaluated using the methodology of Chowdhury et al. Using that model, spontaneous neutron emission is predicted to occur in the range of A = 101 – 103. The Japanese Nuclear Data Compilation terminate their calculations at A = 95. Given these results, single-particle model calculations are extended to encompass these values, and were extended to A = 102 with closure of the 2d3/2 neutron shell. Single particle model calculations predict that A = 87 – 102 neutron excess germanium systems form bound systems that have limiting beta decay half-lives in the range of 0.853 – 32.0 ms. Model half-life results for the A = 87 – 95 germanium nuclei are within a factor of about two of the predictions of the Japanese Nuclear Data Compilation calculations.

The outstanding properties of high-purity germanium (HPGe) detectors, such as excellent energy resolution, high energy sensitivity, and a low background-to-signal ratio, make them essential and ideal candidates for detecting particle signatures in nuclear processes such as neutrino-less double beta decay (textit{0}nu beta beta). However, the presence of defects and impurities in HPGe crystals can lead to charge trapping, which affects carrier mobility and results in significant energy resolution degradation. In this work, we employ density functional theory with a hybrid functional to study the energetics of possible point defects in Ge. Our findings indicate that group-V impurities form more readily in Ge compared to vacancy and interstitial of Ge. Unlike N dopants, which yield deep trap states, P, As, and Sb create shallow traps close to the conduction band edge of Ge. Furthermore, we predict that group-V defects can condense into defect complexes with Ge vacancies. These vacancy-impurity complexes form deep traps in Ge, similar to Ge vacancies, suggesting that both vacancies and vacancy-impurity complexes contribute to charge trapping in these detectors, thereby diminishing their performance.

Abstract Background Medullary thyroid carcinoma (MTC) has limited systemic options in advanced stages. Cancer-associated fibroblasts in tumor stroma in MTC overexpress fibroblast activation protein (FAP). FAP-targeted radioligand therapy (FAPI RLT) thus offers a novel theranostic approach. Alfa particle emitters like 225Actinium (225Ac) deliver high linear energy transfer (LET) to small, aggressive lesions, potentially improving tumor kill, where as bulkier lesions merit use of beta emitter 177lutetium alone or in tandem with 225Actinium. Methods A retrospective analysis of 31 patients with advanced/metastatic MTC treated FAPI RLT at our center was done. These patients had progressive disease despite exhausting TKI options. Pre therapy 68Ga-FAPI PET/CT demonstrated intense uptake in the lesions. 225Ac-FAPi (DOTAGA.Glu.(FAPi)_2) was administered intravenously (3.5–7.0 MBq (95–190 μCi) per treatment cycle) every 8 to 12 weeks. Patients with bulky disease received tandem therapy (two cycles of 177Lu-FAPi dimer ∼5–6 GBq of 177Lu-FAPi each followed by one cycle of 225Ac-FAPi dimer, with each cycle ∼8 weeks apart). Full blood count, renal, and liver function were obtained prior to each cycle.Treatment response was assessed biochemically (serum calcitonin and CEA) and by 68Gallium FAPI-PET/CT every 2 cycles. Progression-free survival (PFS) and overall survival (OS) were calculated from first FAPI therapy, with a follow-up duration up to 3 years. Adverse events were graded by CTCAE v5.0. Results Among 14(∼45%) MTC patients receiving tandem 177Lu/225Ac-FAPi dimer therapy, 68% patients had ∼ 52 to 67% decline in serum calcitonin and CEA levels while 17(∼55%) patients who received only 225Ac-FAPi dimer therapy demonstrated 46 to 61 % reduction in serum calcitonin and CEA levels. Restaging 68Ga-FAPi PET/CT in showed partial metabolic responses in 62.5% of patients and stable disease in 20% patients. A median PFS of ∼32 months and median OS of ∼37 months was observed. A substantial percentage of treated patients remained progression-free at 3 years post-therapy, though subsequent PFS data are awaited. Treatment was generally well tolerated with grade III hematologic toxicity observed in few patients in tandem therapy group (anemia in ∼4%, thrombocytopenia in ∼6.5%). Overall, side effects were transient and reversible. The safety profile of 225Ac-FAPI and tandem therapy mostly includes CTCAE v5.0 grade 1–2 effects. Conclusion Our study suggests FAPI RLT as an promising salvage option for advanced MTC. A substantial tumor response rate (by biochemical and PET criteria) and median PFS on the order of 2 to 3 years were observed. The safety profile appears favorable, with few low grade toxicities, mainly hematological. We conclude that tandem 177Lu/225Ac-FAPI or 225Ac-FAPI therapy can achieve encouraging disease control in carefully selected FAP-positive MTC patients, with durable PFS and OS benefits and acceptable toxicity. Citation Format: Dr Nitin Gupta. 225Actinium and tandem 177Lutetium/225Actinium - FAPi therapy in medullary thyroid carcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: The Rise in Early-Onset Cancers—Knowledge Gaps and Research Opportunities; 2025 Dec 10-13; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(23_Suppl):Abstract nr A013.

Evaluation of radioactivity levels and lifetime cancer risk assessment in drinking water of Dera Ghazi Khan, Pakistan.

Monitoring of natural radionuclides in water samples from LASU aquaculture and water plant.

Internal bremsstrahlung in beta decays.

Abstract For several years, the R&D program called R2D2 (Radial Detector for Rare Decays) has aimed to develop a high-pressure single-anode TPC to search for neutrinoless beta double-decay of the 136 Xe and which could achieve a sensitivity of a few meV in effective mass conjectured for the inverted hierarchy scenario. We present the results obtained for both spherical and cylindrical TPC designs with different anode dimensions, and operated with pressures up to ten bars in argon and xenon gases. The ton-scale principle design is presented as well as a future evolution of the concept to possibly measure other double beta decay isotopes after Xe measurement.

The determination of experimental sensitivity is a key step in the search for neutrinoless double beta decay (0νββ), providing a quantitative benchmark for detector design. Two commonly used statistical approaches are the counting method, which estimates sensitivity from the number of events in a predefined region of interest, and the fitting method, which extracts the signal contribution by fitting the full energy spectrum. In this work, we investigate both discovery sensitivity and exclusion sensitivity within these two approaches. Through statistical derivation and simulation verification, we show that the relative performance of the methods depends on both energy resolution and exposure, while at higher exposures the fitting method consistently yields more stringent sensitivity. These results provide guidance for selecting the optimal statistical method in future 0νββ experiments.

Measurement of the 147Pm beta decay spectrum with a 4π Si(Li) beta spectrometer.

The quantitative mapping of radioisotopes in solids is crucial for understanding their microscale localization and migration. However, conventional radiometric and mass spectrometric techniques are only capable of bulk measurements without spatial resolution. Imaging plates provide spatial resolution, but they lack selectivity and cannot quantify radioisotopes that only emit beta radiation, such as 90Sr. Here, the first system for isotope-specific quantitative mapping of a pure beta emitter is demonstrated, integrating online isotope dilution (ID) with laser ablation inductively coupled plasma tandem mass spectrometry (LA-ICP-MS/MS). In a case study, ultratrace levels of 90Sr were accurately quantified without requiring matrix-matched certified reference materials (CRMs) for calibration or chemical separation. Severe isobaric/polyatomic interference (e.g., 90Zr+, 74Ge16O+, 89Y1H+, and 58Ni16O2+) was efficiently suppressed by O2 reaction in a dynamic reaction cell, which greatly improved the abundance sensitivity and allowed subfemtogram amounts of 90Sr to be quantitatively imaged. The background equivalent concentration (BEC) was 0.14 ng g-1 (equivalent to 7.0 × 102 Bq g-1) per data point, and the measurement time was within 1 s. Validation with CRMs and 90Sr samples confirmed accuracy of 88-116% relative to reference values. The proposed system is a versatile platform that can be applied to the practical mapping of radioactive solids, which has broad implications for nuclear waste disposal, environmental remediation, and radiation protection.

We present a unified model of quarks and leptons with modular S 3 flavor symmetry, where the two lightest family masses are naturally suppressed via a Pati-Salam version of the type I seesaw mechanism, mediated through heavier vectorlike fermions. Majorana neutrino masses are further suppressed through a double seesaw mechanism. The viable parameter space has a preferred range of the modulus field with Im ( τ ) ∼ 2 , leading to successful fermion masses and mixing. The prediction for neutrinoless double beta decay is partly within the reach of the nEXO experiment. In particular, the Dirac C P violating neutrino oscillation phase is predicted to lie in the range δ C P ν ∼ 270 ° − 360 ° .

This article explores a novel idea by proposing a unified semi-empirical formula for both alpha and beta decay in unstable nuclei. A key feature of this formula is its simplicity and ability to provide highly accurate decay information based solely on the fundamental properties of the parent nucleus. Another remarkable aspect is the large number of isotopes used to fit the formula, exceeding 2200. This extensive data set has significantly enhanced the formula’s reliability. Additionally, we have included thorough comparisons between our results and those of other studies, which clearly demonstrate the higher performance of our formula. Even while our suggested formula is applicable to beta decay, the other formulae were particularly created for alpha decay.

IntroductionRadioembolisation (RE) is gaining traction as a robust treatment option for patients with hepatocellular cancer (HCC) across all cancer stages. RE allows the delivery of targeted high-dose radiation directly to tumours, with relative sparing of the surrounding liver tissue. Traditionally, radiation has been delivered using 90Yttrium ([90Y]Y)-labelled microspheres, either glass or resin. The success of RE is dependent on the dose delivered to the tumour. When using [90Y]Y microspheres, dose prediction is calculated through a 99mTechnitium ([99mTc]Tc)-macroaggregated albumin (MAA) scan, which allows the calculation of the dose to be administered to the tumour. However, [99mTc]Tc-MAA is not a true surrogate of [90Y]Y microspheres, and this will impact on the final dose delivered. [166Ho]Ho, like [90Y]Y, is a beta emitter but unlike [90Y]Y also emits gamma-radiation, allowing for quantitative nuclear imaging. The primary aim of this pilot study was to investigate the safety and efficacy of dosimetry-based individualised 166Holmium ([166Ho]Ho-RE) in patients with HCC.Methods and analysis15 eligible participants will be recruited to receive [166Ho]Ho-RE. The primary objective is to establish the toxicity profile of dosimetry-based individualised [166Ho]Ho-RE. The secondary objective is to assess efficacy as measured by modified Response Evaluation Criteria in Solid Tumours (mRECIST) and Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 criteria. Additional exploratory objectives include quality of life assessment and identification of a radiomic signature of response. The results from this study will be combined with the prospective iHEPAR study to form a larger analysis.Ethics and disseminationThe study has received approval from the East Midlands—Nottingham 1 Research Ethics Committee—approval number 23/EM/0239. The study will be performed in compliance with the Declaration of Helsinki and the principles of Good Clinical Practice. Signed informed consent will be obtained from each patient before study entry. The results will be disseminated through publication in a peer-reviewed scientific journal.Trial registration numberClinicaltrials.gov NCT06302400.