Tue·Feb 13, 2024Tuesday·February 13, 2024

1. 01*

   Decay rate measurements ${}^{137}$Cs at Jánossy Underground Research Laboratory

   Edit Fenyvesi · Gergely Gábor Barnaföldi🇭🇺 · Gábor Gyula Kiss🇭🇺 · Dénes Molnár

   The question whether an annual modulation is observable during nuclear decay rate measurements has long been the subject of research. One of the possible explanations for the annual variations would be the effect of solar neutrinos, the flux of which changes in correlation with the Earth-Sun distance. A decay rate measurement with a ${}^{137}$Cs source and a HPGe detector is currently being conducted 30 meters below the ground at Jánossy Underground Research Laboratory (Csillebérc, Hungary). The laboratory is part of the Vesztergombi High Energy Laboratory (VLAB), one of the TOP 50 research infrastructures in Hungary. From October 2022 to March 2023, data of six months' worth has been collected, and hence this is a new opportunity to check whether the annual variation in decay rate can be observed. The laboratory, the experiment, the data processing method, and the first results are presented in this study.

   nucl-exPoS(2024)·1 citation
2. 02*

   Flavor Factorization at Two-Loops

   Andrew J. Larkoski🇺🇸

   Recently, a factorization theorem was proposed for partonic flavor evolution as defined by the net flavor of the Winner-Take-All axis of a jet. We validate the factorization theorem through explicit calculation at two-loop order, and in the process extract all anomalous dimensions and renormalization factors for any ultraviolet-to-infrared flavor transition at this order. These results can then be used to extract the renormalized hard function for flavored jet production at next-to-next-to-leading order for any process of interest.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2024)·2 citations
3. 03*

   First Study of the PIKACHU Project: Development and Evaluation of High-Purity Gd${}_3$Ga${}_3$Al${}_2$O${}_{12}$:Ce Crystals for ${}^{160}$Gd Double Beta Decay Search

   Takumi Omori🇯🇵 · Takashi Iida🇯🇵 · Azusa Gando🇯🇵 · Keishi Hosokawa🇯🇵 · Kei Kamada🇯🇵 · Keita Mizukoshi🇯🇵 · Yasuhiro Shoji🇯🇵 · Masao Yoshino🇯🇵 · Ken-Ichi Fushimi🇯🇵 · Hisanori Suzuki🇯🇵 · Kotaro Takahashi🇯🇵

   Uncovering neutrinoless double beta decay (0$\nu$2$\beta$) is crucial for confirming neutrinos' Majorana characteristics. The decay rate of 0$\nu \beta \beta$ is theoretically uncertain, influenced by nuclear matrix elements that vary across nuclides. To reduce this uncertainty, precise measurement of the half-life of neutrino-emitting double beta decay (2$\nu$2$\beta$) in different nuclides is essential. We have launched the PIKACHU (Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences) project to fabricate high-purity Ce-doped Gd${}_3$Ga${}_3$Al${}_2$O${}_{12}$ (GAGG) single crystals and use them to study the double beta decay of ${}^{160}$Gd. Predictions from two theoretical models on nuclear matrix element calculations for 2$\nu$2$\beta$ in ${}^{160}$Gd show a significant discrepancy in estimated half-lives, differing by approximately an order of magnitude. If the lower half-life estimation holds true, detecting 2$\nu$2$\beta$ in ${}^{160}$Gd could be achievable with a sensitivity enhancement slightly more than an order of magnitude compared to prior investigations using Ce-doped Gd${}_2$SiO${}_5$ (GSO) crystal. We have successfully developed GAGG crystals with purity levels surpassing previous standards through refined purification and selection of raw materials. Our experiments with these crystals indicate the feasibility of reaching sensitivities exceeding those of earlier studies. This paper discusses the ongoing development and scintillator performance evaluation of High-purity GAGG crystals, along with the anticipated future prospects of the PIKACHU experiment.

   ↳ physics.ins-dethep-exnucl-exPTEP(2024)·10 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.