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1. Demonstration of event position reconstruction based on diffusion in the NEXT-white detector

   https://doi.org/10.1140/epjc/s10052-024-12865-9  

   Haefner, J; Navarro, K E; Guenette, R; Jones, B_J P; Tripathi, A; Adams, C; Almazán, H; Álvarez, V; Aparicio, B; Aranburu, A I; et al (May 2024, The European Physical Journal C)

   Noble element time projection chambers are a leading technology for rare event detection in physics, such as for dark matter and neutrinoless double beta decay searches. Time projection chambers typically assign event position in the drift direction using the relative timing of prompt scintillation and delayed charge collection signals, allowing for reconstruction of an absolute position in the drift direction. In this paper, alternate methods for assigning event drift distance via quantification of electron diffusion in a pure high pressure xenon gas time projection chamber are explored. Data from the NEXT-White detector demonstrate the ability to achieve good position assignment accuracy for both high- and low-energy events. Using point-like energy deposits from$$^{83\textrm{m}}$$ ${}^{83\text{m}}$Kr calibration electron captures ($$E\sim 45$$ $E\sim 45$ keV), the position of origin of low-energy events is determined to 2 cm precision with bias$$< 1~$$ $<1$mm. A convolutional neural network approach is then used to quantify diffusion for longer tracks ($$E\ge ~1.5$$ $E\ge 1.5$ MeV), from radiogenic electrons, yielding a precision of 3 cm on the event barycenter. The precision achieved with these methods indicates the feasibility energy calibrations of better than 1% FWHM at Q$$_{\beta \beta }$$ ${}_{\beta \beta }$in pure xenon, as well as the potential for event fiducialization in large future detectors using an alternate method that does not rely on primary scintillation. 

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2. Spectroscopic investigation of $$^{54}$$Cr via $$\alpha $$-transfer reaction

   https://doi.org/10.1140/epja/s10050-025-01619-0  

   Das, Biswajit; Kundu, A.; Palit, R.; Dey, P.; Malik, Vishal; Garg, U.; Negi, D.; Laskar, S_R; Santra, Rajkumar; Jadhav, S_K; et al (June 2025, The European Physical Journal A)

   Abstract Low-lying states in$$^{54}$$ $_{}^{54}$Cr have been investigated via the$$\alpha $$ $\alpha$-transfer reaction$$^{50}$$ $_{}^{50}$Ti($$^{7}$$ $_{}^7$Li,t) at a bombarding energy of 20 MeV. The exclusive$$\alpha $$ $\alpha$-transfer channel is separated from other reaction channels through the appropriate energy gate on the complementary particle, triton. Levels of$$^{54}$$ $_{}^{54}$Cr populated exclusively by the$$\alpha $$ $\alpha$-transfer process could be identified up to$$\approx $$ $\approx$5 MeV excitation energy and angular momentum up to$$(8)^{+}$$ ${\left(8\right)}^{+}$, by identifying the corresponding known$$\gamma $$ $\gamma$-rays. These include multiple low-lying non-yrast 2$$^+$$ $_{}^{+}$and 4$$^+$$ $_{}^{+}$states, which would otherwise be unfavorable via fusion evaporation reactions. The feeding-subtracted$$\gamma $$ $\gamma$-ray yields have been extracted to estimate the population of various excited states through the transfer process. The measured integrated transfer cross sections for all the observed yrast and non-yrast states are compared with Coupled Channels calculations usingfrescoto extract the$$\alpha $$ $\alpha$+$$^{50}$$ $_{}^{50}$Ti core spectroscopic factors. For the yrast states, a higher$$\alpha $$ $\alpha$+core overlap is seen for the$$2^+$$ $2^{+}$and$$4^+$$ $4^{+}$states, while it is seen to be less favorable for the$$6^+$$ $6^{+}$and$$(8)^+$$ ${\left(8\right)}^{+}$states when$$\alpha $$ $\alpha$-transfer is considered to occur predominantly as a direct one-step process to the$$^{50}$$ $_{}^{50}$Ti core ground state. The yrast$$2^+$$ $2^{+}$, and$$4^+$$ $4^{+}$states are predominantly populated by single-step transfer, while for the states with spin$$\ge $$ $\ge$5, the possibility of core excitation followed by$$\alpha $$ $\alpha$-transfer shows a larger$$\alpha $$ $\alpha$-core overlap. For the non-yrast$$0^+$$ $0^{+}$,$$2^+$$ $2^{+}$, and$$4^+$$ $4^{+}$states, single-step transfer shows moderate to small$$\alpha $$ $\alpha$-core overlap. No higher spin non-yrast states are observed. 

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3. First demonstration of a TES based cryogenic Li$$_2$$MoO$$_4$$ detector for neutrinoless double beta decay search

   https://doi.org/10.1140/epjc/s10052-025-13844-4  

   Bratrud, G.; Chang, C_L; Chen, R.; Cudmore, E.; Figueroa-Feliciano, E.; Hong, Z.; Kennard, K_T; Lewis, S.; Lisovenko, M.; Mateo, L_O; et al (January 2025, The European Physical Journal C)

   Abstract Cryogenic calorimetric experiments to search for neutrinoless double-beta decay ($$0\nu \beta \beta $$ $0\nu \beta \beta$) are highly competitive, scalable and versatile in isotope. The largest planned detector array, CUPID, is comprised of about 1500 individual Li$$_{2}$$ $_2^{}$$$^{100}$$ $_{}^{100}$MoO$$_4$$ $_4^{}$detector modules with a further scale up envisioned for a follow up experiment (CUPID-1T). In this article, we present a novel detector concept targeting this second stage with a low impedance TES based readout for the Li$$_2$$ $_2^{}$MoO$$_4$$ $_4^{}$absorber that is easily mass-produced and lends itself to a multiplexed readout. We present the detector design and results from a first prototype detector operated at the NEXUS shallow underground facility at Fermilab. The detector is a 2-cm-side cube with 21 g mass that is strongly thermally coupled to its readout chip to allow rise-times of$$\sim $$ $\sim$0.5 ms. This design is more than one order of magnitude faster than present NTD based detectors and is hence expected to effectively mitigate backgrounds generated through the pile-up of two independent two neutrino decay events coinciding close in time. Together with a baseline resolution of 1.95 keV (FWHM) these performance parameters extrapolate to a background index from pile-up as low as$$5\cdot 10^{-6}$$ $5·{10}^{-6}$ counts/keV/kg/yr in CUPID size crystals. The detector was calibrated up to the MeV region showing sufficient dynamic range for$$0\nu \beta \beta $$ $0\nu \beta \beta$searches. In combination with a SuperCDMS HVeV detector this setup also allowed us to perform a precision measurement of the scintillation time constants of Li$$_2$$ $_2^{}$MoO$$_4$$ $_4^{}$, which showed a primary component with a fast O(20 $$\upmu $$ $\mu$s) time scale. 

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4. Random 3-manifolds have no totally geodesic submanifolds

   https://doi.org/10.1007/s10455-025-09998-9  

   El-Hasan, Hasan M; Wilhelm, Frederick (May 2025, Annals of Global Analysis and Geometry)

   Agricola, Ilka; Bögelein, Verena (Ed.)

   Abstract Murphy and the second author showed that a generic closed Riemannian manifold has no totally geodesic submanifolds, provided the ambient space is at least four dimensional. Lytchak and Petrunin established a similar result in dimension 3. For the higher dimensional result, the “generic set” is open and dense in the$$C^{q}$$ $C^q$–topology for any$$q\ge 2.$$ $q\ge 2.$In Lytchak and Petrunin’s work, the “generic set” is a dense$$G_{\delta }$$ $G_{\delta }$in the$$C^{q}$$ $C^q$–topology for any$$q\ge 2.$$ $q\ge 2.$Here we show that the set of such metrics on a compact 3–manifold actually contains a set that is that is open and dense set in the$$C^{q}$$ $C^q$–topology, provided$$q\ge 3.$$ $q\ge 3.$ 

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5. Modular apparatus for nuclear reactions spectroscopy (MARS): characterization and first application to determine $$^{12}$$C($$^6$$Li,$$^4$$He)$$^{14}\hbox {N}^{g.s}$$ nuclear reaction cross sections

   https://doi.org/10.1140/epjp/s13360-025-06305-0  

   Garrido-Gómez, L; Vegas-Díaz, A; Alvarez, M_A G; Fernández-García, J P; Fernández, B; Ferrer, F J; Lopez-Aires, D (May 2025, The European Physical Journal Plus)

   Abstract This work presents MARS (Modular apparatus for nuclear reactions spectroscopy) and its characterization prior to its first application to measure$$^6$$ $_{}^6$Li+$$^{12}$$ $_{}^{12}$C nuclear reactions. Measurements were performed at the 3 MV tandem accelerator of the CNA (National Accelerator Center), in Seville, Spain. The$$^{6}$$ $_{}^6$Li projectiles were accelerated at energies around the$$^6$$ $_{}^6$Li+$$^{12}$$ $_{}^{12}$C Coulomb barrier ($$V^{\text {cm}}_{B}\sim 3.0$$ $V_B^{\text{cm}}\sim 3.0$MeV - center of mass and$$V^{\text {lab}}_{B}\sim 4.5$$ $V_B^{\text{lab}}\sim 4.5$MeV - laboratory frame). Using a$$^{6}\hbox {Li}^{2+}$$ $_{}^6{\text{Li}}^{2+}$beam, we measured at 13 laboratory energies from 4.00 to 7.75 MeV. Thus, we present the excitation function of$$^{12}$$ $_{}^{12}$C($$^6$$ $_{}^6$Li,$$^4$$ $_{}^4$He)$$^{14}\hbox {N}^{g.s.}$$ $_{}^{14}{\text{N}}^{g.s.}$reaction, at 2 backward angles ($$110.0^\circ $$ $110.0^{\circ }$and$$140.0^\circ $$ $140.0^{\circ }$). The projectile dissociation, leading to this reaction, increases with the bombarding energies around the Coulomb barrier. This dissociation is favored at an optimum energy$$E_{b}^{\text {op}}$$ $E_b^{\text{op}}$$$\ge $$ $\ge$$$V_{B}$$ $V_B$+$$|Q_{bu}|$$ $|Q_{\mathrm{bu}}|$, where$$V_{B}$$ $V_B$is the Coulomb barrier of the system, and$$|Q_{bu}|$$ $|Q_{\mathrm{bu}}|$is the module ofQ-value for the$$^6$$ $_{}^6$Li dissociation into$$^4$$ $_{}^4$He+$$^2$$ $_{}^2$H. This result corroborates a systematic analysis of weakly bound projectiles reacting on several targets [1]. 

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