Status of Anti-Neutrino Detection Technology for Reactor Monitoring in ROK

Bo-Young Han,Jinyu Kim,Gwang-Min Sun 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

Over the past decades, particle physics has made significant progress in characterizing neutrinos even if neutrinos have extremely small cross-section (~10-44 cm2), allowing them to penetrate any object. More recently, neutrino detection and analysis have indeed become valuable tools in various aspects of nuclear science and technology. Neutrinos are detected using various methods, including Inverse Beta Decay (IBD), Neutrino-electron scattering, and Coherent Neutrino-Nucleus Scattering (CNNS). For the detection of anti-neutrinos from nuclear reactor, the Inverse Beta Decay (IBD) is commonly considered with scintillators. Notable experiments in Korea, such as RENO and NEOS, have been conducted using the IBD method at the Hanbit Nuclear Power Plant since 2006. Additionally, the NEON experiment, which employs CNNS, which has a significantly larger reaction cross-section than IBD but its low-energy signal detection difficulty, has been ongoing since 2021. Based on the results of NEOS (2015-2020) the signal to noise is ~30 and IBD detection rate is ~2000 counts per day. The IBD event in nuclear power plants provides valuable information about reactor behavior. IBD count rates are in good agreement with the thermal power of the reactor. Furthermore, the neutrino energy spectrum can be used to estimate the fission isotope ratio of the reactor core, showing promise for obtaining reactor core information from antineutrino detection techniques. Neutrino detection in nuclear facilities provides valuable information about reactor behavior. However, as a surveillance technology neutrino detection faces challenges due to the very low cross-section, requiring efforts to overcome limitations related to detector size and signal acquisition time. In 2008, the International Atomic Energy Agency (IAEA) included neutrino detection in its Research and Development (R&D) program for reactor safeguards. In January 2023, the IAEA organized a “Technical Meeting on Nuclear Data Needs for Antineutrino Spectra Applications” to discuss the latest developments and research results in this field. In summary, the use of neutrino detection in the nuclear field, particularly for reactor monitoring and safeguarding, has advanced significantly. Ongoing research and collaboration are expected to enhance our understanding of neutrinos and their applications in nuclear science and technology.

중성미자 진동실험과 비활성 중성미자

김시연 한국물리학회 2016 새물리 Vol.66 No.8

Sterile neutrinos, which are neutral under the weak interaction, are new fermions beyond the standard model. Although experimental anomalies hinted at their existence, their interactions are still completely unknown, and they belong to the class of dark matter. On the other hand, they can mix with weak-interaction-active neutrinos, and their masses are assumed to be heavier than three generations of neutrinos, so their presence should be revealed in the form of probability oscillations with active neutrinos. We review various neutrino oscillation experiments that can verify the existence of light sterile neutrinos, focusing on the differences and the similarities between reactor neutrino experiments and accelerator neutrino experiments. The number of sterile neutrinos can be more than one. As a canonical approach, in this review, only the three-plus-one scheme is adopted to make prediction for future experiments. 약한상호작용을 하지 않는 비활성 중성미자는 몇몇 비정상현상을 보인 실험결과에 근거하여 존재할 것이라고 소개된 새로운 페르미온이다. 비활성 중성미자의 상호작용은 전혀 알려져 있지 않기 때문에, 여전히 암흑물질의 범위에 속한다. 한편, 약한상호작용의 활성 중성미자와 혼합할 수 있고, 그것들보다 더 큰 질량을 가질 것으로 예측되므로, 활성 중성미자와의 확률진동의 형태로 그 존재가 드러날 수 밖에 없다. 비활성 중성미자의 존재를 검증할 수 있는 중성미자 진동실험의 원리와 실례를 원자로중성미자 실험과 가속기중성미자 실험의 차이와 보완적 역할을 비교하여 검토한다. 비활성 중성미자의 개수가 하나보다 많을 수 있지만, 이 리뷰에서는 기본적인 접근방법으로 활성 세 개와 비활성 한 개의 모델만 채택하여 향후 실험의 예측을 이끌어 낼 것이다.

Calculation of Low-Energy Reactor Neutrino Spectra for Reactor Neutrino Experiments

Riyana, Eka Sapta,Suda, Shoya,Ishibashi, Kenji,Matsuura, Hideaki,Katakura, Jun-ichi The Korean Association for Radiation Protection 2016 방사선방어학회지 Vol.41 No.2

Background: Nuclear reactors produce a great number of antielectron neutrinos mainly from beta-decay chains of fission products. Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may take part in special weak interactions. We calculate reactor antineutrino spectra especially in the low energy region. In this work we present neutrino spectrum from a typical pressurized water reactor (PWR) reactor core. Materials and Methods: To calculate neutrino spectra, we need information about all generated nuclides that emit neutrinos. They are mainly fission fragments, reaction products and trans-uranium nuclides that undergo negative beta decay. Information in relation to trans-uranium nuclide compositions and its evolution in time (burn-up process) were provided by a reactor code MVP-BURN. We used typical PWR parameter input for MVP-BURN code and assumed the reactor to be operated continuously for 1 year (12 months) in a steady thermal power (3.4 GWth). The PWR has three fuel compositions of 2.0, 3.5 and 4.1 wt% $^{235}U$ contents. For preliminary calculation we adopted a standard burn-up chain model provided by MVP-BURN. The chain model treated 21 heavy nuclides and 50 fission products. The MVB-BURN code utilized JENDL 3.3 as nuclear data library. Results and Discussion: We confirm that the antielectron neutrino flux in the low energy region increases with burn-up of nuclear fuel. The antielectron-neutrino spectrum in low energy region is influenced by beta emitter nuclides with low Q value in beta decay (e.g. $^{241}Pu$) which is influenced by burp-up level: Low energy antielectron-neutrino spectra or emission rates increase when beta emitters with low Q value in beta decay accumulate Conclusion: Our result shows the flux of low energy reactor neutrinos increases with burn-up of nuclear fuel.

$$\nu$$Oscillation: a software package for computation and simulation of neutrino oscillation and detection

Jang Seunghyeok,원은일,Lee Kyungmin,Jeon Eunju,Ko Young Ju 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.85 No.5

The design of neutrino experiments and the analysis of neutrino data rely on precise computations of neutrino oscillations and scattering processes in general. Motivated by this, we developed a unifed software package that calculates the expected number and energy spectrum of neutrino events in the liquid scintillation detector taking into account the neutrino fux at production, the oscillations of neutrinos during propagation and their interactions in the detectors. We also implemented the calculation of neutrino fux from nuclear reactors, the Sun, and radioactive isotopes to explorer various experimental setups using a single package. This software package is validated by reproducing the result of calculations and observations in other publications. We also demonstrate the feasibility of this package by calculating the sensitivity of a liquid scintillation detector, currently in planning, to the sterile neutrinos. This work is expected to be utilized to identify the physics potential and optimize the design of future neutrino experiments.

Estimating Uncertainties in the Reactor Neutrino Directionality Using Liquid Scintillator with Monte Carlo Simulation

Jun Hu Seo,Kyung Kwang Joo,신창동,Atif Zohaib 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.2

This paper describes in detail the uncertainties due to several factors that may affect the direction vector of a reactor neutrino in a liquid scintillation detector. The reactor neutrino direction vector was reconstructed through a charge weighting method. The paper simulates the response of gadolinium-loaded, liquid scintillator detector to reactor electron anti-neutrinos. The reaction is based on neutrino capture on hydro-genic protons of inverse beta decay process in the scintillator. A Cherenkov radiation detector can reconstruct the directional information of incident neutrinos relatively well, compared to the liquid scintillation detector. Statistics, spatial resolution, neutrino energy, and multi-reactor and multi-detectors are examined by using Monte Carlo simulation based on the cylindrical liquid scintillating detector model. Furthermore, this simulated model is detailed down to the optical processes, and the source of reactor fuel composition. Finally, one of the main goals is to provide the potential of the detector to measure the origin direction of the incident neutrino. Furthermore, our intention is to help understanding of various uncertainties of the neutrino directionality study for the future massive liquid scintillating neutrino detectors.

Neutrinoless Double Beta Decay and Light Sterile Neutrino

C. H. Jang,B. J. Kim,Y. J. Ko,K. Siyeon 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.11

The recent neutrino experiment results show a preference on normal mass ordering of neutrinos. The global efforts to search for neutrinoless double beta decays undergo a broad gap with the approach to the prediction in three-neutrino framework based on the normal ordering. Current research is to show that it is possible to find a neutrinoless double beta decay signal even with normal ordered neutrino masses. We propose the existence of light sterile neutrino as a solution to the higher effective mass of electron neutrino expected by experiments under operation. A few short-baseline oscillation experiments gave rise to exclusion bound to the mass of sterile neutrino and its mixing with the lightest neutrino. It is demonstrated that results of neutrinoless double beta decays can also narrow down the ranges of the mass and the mixing angle of sterile neutrino.

액체 신틸레이터를 이용한 초신성 확산 배경 중성미자 관측

박명렬 한국물리학회 2019 새물리 Vol.69 No.7

The core collapse supernova (CCSN) releases most of the explosive energy through neutrinos. Therefore, the detection of the CCSN neutrino is essential to understand the temporal evolution of the CCSN. However, since it is difficult to detect neutrinos originating from a CCSN, the possibility of detecting diffuse supernovae neutrino background (DSNB) emitted from the supernovae in the Universe after the Big Bang is discussed. The results show that 10−3 events per year DSNB-induced neutrino events are expected using a 20 t gadolinium-loaded liquid neutrino detector currently used. However, in case of the CCSN being near at hand, the neutrino detector can detect about 1,200 events during the first 10 seconds. This means that the neutrino detector can operate as an alarm system for the CCSN in close proximity to the Sun. 중심핵 붕괴 초신성 (core collapse supernova, CCSN) 은 중성미자를 통해 대부분의 폭발 에너지를방출하기 때문에 CCSN으로 부터 방출되는 중성미자 검출은 CCSN의 시간적 진화를 이해하는 데 필수적이다. 그러나 하나의 CCSN에서 유래한 중성미자를 검출하는 것은 매우 어렵기 때문에 우주 형성 후지금까지 발생한 CCSN에서 방출되어 우주공간에 확산된 초신성 중성미자 (diffuse supernovae neutrino background, DSNB)들을 발견 할 가능성에 대해 살펴보았다. 이 연구를 통헤 20톤 규모의 중소형 중성미자 검출기로는 DSNB를 일 년에 10−3 개 정도를 검출하기 때문에 효과적이지 않았다. 하지만 지구근처에서 발생한 CCSN에 대해서는 최초 10초 동안 약 1,200 여개의 중성미자 신호를 검출할 수 있기때문에 초신성 폭발 경보 시스템으로 작동 할 수 있다는 것을 보았다.

암흑물질로서의 비활성 중성미자

강신규 한국물리학회 2016 새물리 Vol.66 No.8

비활성 중성미자의 암흑물질 후보 입자가 될 수 있는 가능성에 대해 논의한다. 비활성 중성미자가 생성될 수 있는 3가지 생성 메카니즘에 대해 알아본다: Dodelson-Widrow (DW) mechanism, Shi-Fuller (SF) mechanism, 스칼라장의 붕괴로부터 비활성 중성미자의 생성. DW 메카니즘은 표준 모형의 중성미자와 비활성 중성미자 사이의 진동에 의해 비활성 중성미자가 생성되는 메카니즘이며, 이렇게 생성된 비활성 중성미자는 X-선 관측 결과와 Lyman-$\alpha$ 관측 결과를 동시에 만족시킬 수 없다. SF 메카니즘은 우주 초기에 충분한 양의 렙톤 비대칭이 구현되었다는 가정하에 MSW 공명에 의한 중성미자 진동을 통하여 비활성 중성미자가 생성되는 메카니즘으로 DW 메카니즘의 문제점을 극복할 수 있게 한다. 한편, 비활성 중성미자는 스칼라장의 붕괴를 통하여 충분한 양이 생성될 수 있다. 비활성 중성미자의 평균 운동량을 계산함으로써 생성 메카니즘에 따라 생성된 비활성 중성미자가 얼만큼 뜨거운지 아니면 차가운지를 알 수 있다. 비활성 중성미자는 X-선 광자를 방출하면서 붕괴될 수 있으며, 이렇게 방출된 X-선을 관측함으로써 비활성 중성미자 암흑물질을 탐색할 수 있는 가능성에 대해 논의한다. We review how the sterile neutrino can be a dark-matter candidate. We study three possible production mechanisms for sterile-neutrino dark-matter: the Dodelson-Widrow (DW) mechanism, the Shi-Fuller (SF) mechanism, and production via the decay of the scalar field. Sterile-neutrino dark matter produced only through the DW mechanism can be eliminated based on a combination of X-ray and Lyman-$\alpha$ measurements. The SF mechanism can ameliorate the problem occurring in the case of DW mechanism. The other alternative is the production of sterile neutrinos via the decay of the scalar field. By estimating the average momentum of the sterile neutrino, we investigate whether sterile neutrinos can be warm dark matter or not. We briefly discuss how sterile neutrinos can be probed indirectly by using X-ray telescopes that can detect the photon line signal produced from radiative decay of the sterile neutrino.

COSMOLOGY WITH MASSIVE NEUTRINOS: CHALLENGES TO THE STANDARD ΛCDM PARADIGM

ROSSI, GRAZIANO The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

Determining the absolute neutrino mass scale and the neutrino mass hierarchy are central goals in particle physics, with important implications for the Standard Model. However, the final answer may come from cosmology, as laboratory experiments provide measurements for two of the squared mass differences and a stringent lower bound on the total neutrino mass - but the upper bound is still poorly constrained, even when considering forecasted results from future probes. Cosmological tracers are very sensitive to neutrino properties and their total mass, because massive neutrinos produce a specific redshift-and scale-dependent signature in the power spectrum of the matter and galaxy distributions. Stringent upper limits on ${\sum}m_v$ will be essential for understanding the neutrino sector, and will nicely complement particle physics results. To this end, we describe here a series of cosmological hydrodynamical simulations which include massive neutrinos, specifically designed to meet the requirements of the Baryon Acoustic Spectroscopic Survey (BOSS) and focused on the Lyman-${\alpha}$ ($Ly{\alpha}$) forest - also a useful theoretical ground for upcoming surveys such as SDSS-IV/eBOSS and DESI. We then briefly highlight the remarkable constraining power of the $Ly{\alpha}$ forest in terms of the total neutrino mass, when combined with other state-of-the-art cosmological probes, leaving to a stringent upper bound on ${\sum}m_v$.

원자로 중성미자를 이용한 중성미자 질량계층 기초연구

박명렬,최준호 한국물리학회 2014 새물리 Vol.64 No.8

We report experimental possibilities for determining the neutrino mass hierarchy by using reactor neutrinos. A baseline that is about 58 km from the reactor(s) is most sensitive to the neutrino mass hierarchy when the position of the peak in the neutrino energy spectrum from inverse β-decay and a parameterized reactor neutrino flux are applied. By applying Fourier sine and cosine transformations to the event rate from neutrino oscillation probability, Pee(L/Enu), we could extract signals of the neutrino mass hierarchy in δ m^{2} space from the different frequency oscillations. 원자로 중성미자를 이용하여 중성미자 질량계층을 연구할 수 있는 실험적 가능성을 살펴보았다. 원자로 발생 반전자 중성미자 선속과 역베타 붕괴반응을 통해 검출된 반전자 중성미자 스펙트럼의 마루 (peak) 에너지를 적용하였을때, 약 58 km의 중성미자 비행거리가 중성미자 질량계층에 가장 민감하다는 것을 알 수 있었다. 이 비행거리 부근에서 질량계층에 따라 달라지는 중성미자 진동확률, Pee(L/E_nu}를 δm²에 대한 푸리에 사인 및 코사인 변환을 적용하면 δm² 공간에서 중성미자 질량계층 신호를 구분할 수 있음을 알았다.