Search for sterile neutrinos and measurement of neutrino-argon interactions at the SBN programme

SBN 项目寻找惰性中微子并测量中微子-氩相互作用

• 批准号: 2113282
• 金额: --
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2113282
• 关键词: Search; sterile; neutrinos; measurement; neutrino

There are three known flavours of neutrinos corresponding to the three differentflavours of charged leptons. The number of neutrinos may be determined by observing the decayof the Z boson, since its lifetime is dependent on how many different flavours there are. Thelifetime of the Z boson has been found to be consistent with a three neutrino model . Therehave, however, been a number of experimental results which are not consistent with oscillationsin a three neutrino model. The three main results are the reactor anomaly which refers to theapparent lack of anti-electron neutrinos observed from nuclear reactors, the Gallium anomalywhich refers to the apparent lack of electron neutrinos observed from radioactive sources placedin the Gallium based solar neutrino experiments, SAGE and GALLEX and the apparent excessof electron neutrinos observed by the LSND and MiniBooNE experiments from a predominantlymuon (anti)-neutrino beam . For the reactor anomaly, the ratio of the number of observed anti-electron neutrinos to the predict number was 0.938 _ 0.023. Similarly, the corresponding ratiofor the Gallium anomaly was 0.86 _ 0.05. Both of these ratios equate to about a 2.7_ deviationfrom unity and both anomalies were observed in the case of low energy electron neutrinos andover short baselines of a few meters. The LSND experiment was performed over a baseline of30 m with a beam of muon anti-neutrinos with an energy range of 20-53 MeV. The number ofevents observed corresponded to a 3.8_ excess. The MiniBooNE experiment was performed witha baseline of 540 m and with a beam energy of 700 MeV. The experiment was performed with abeam of muon neutrinos and muon anti-neutrinos. A 3.4_ and 2.8_ excess of events were observedrespectively. These results may be explained by oscillations from at least one additional neutrinostate with a mass splitting. This fourth neutrino state may be interpreted as asterile neutrino (as opposed to the active neutrinos. Unlike the active neutrinos, a sterileneutrino would only interact via gravity and not the weak interaction. As a result of this, a sterileneutrino would not contribute to the rate of decay of the Z boson and would not result in any sortof a signal when passing through a detector .The short baseline neutrino (SBN) programme aims to address the anomalies in the experimental results by establishing whether sterile neutrinos exist. The SBN programme consists ofthree separate liquid argon time projection chambers (LArTPC); the Short Baseline Near Detector(SBND), MicroBooNE and ICARUS. The three detectors are located along the axis of the boosterneutrino beam (BNB) at 110 m, 470 m and 600 m respectively from the neutrino beam source.The BNB initially consist of close to a 100% muon neutrinos and one of the primary goals ofthe programme is to look for e appearance and disappearance. As the near detector, SBNDwill measure the unoscillated flavour content of the BNB, determining its exact characteristics.Additionally, the close proximity of SBND to the beam source allows for the measurement of manyneutrino-argon interactions and thus with such a large data sample the study of these interactionsmay be performed to new levels of precision. The MicroBooNE detector is purposely positionedclose to its predecessor, the MiniBooNe detector, and is attempting to replicate the excess of eventsobserved there. The ICARUS detector will focus on measuring the flavour content of the beamand comparing it with the results of SBND to determine if any discrepancies in the data may beas a result of a sterile neutrino.LArTPC's allow images of particle trajectories and interactions to be recorded. In the caseof the SBN, this happens when a neutrino interacts in the detector, producing particles. If theproduced particles are charged, they will in turn create ionisation track, but if they are neutral,they will travel through the detector unnotice

中微子有三种已知的口味，与带电的三种不同氟氟叶子相对应。中微子的数量可以通过观察Z玻色子的衰减来确定，因为它的寿命取决于有多少不同的口味。发现Z玻色子的theliftime与三个中微子模型一致。然而，已有许多实验结果与三个中微子模型中的振荡不符。三个主要结果是反应堆异常，它是指从核反应器中观察到的抗电子中性群的缺乏，镀具有的镀凝剂是指明显缺乏电子中微子，从放射性来源中观察到的电子中微子，这是从甘露的基于甘露的基于甘露的基于甘露的基于甘露的中微子实验，Sage和Gallex和Gallex和Gallix和Gallix和Gallix和Gallix和Gallix和Gallime和Gallimin和Gallimo solar中微子。 LSND和MiniBoone实验中观察到的明显过量的电子中微子来自主要含量（抗） - 尼特里诺束束。对于反应堆异常，观察到的抗电子中微子与预测数的比率为0.938 _ 0.023。类似地，相应的比率镀凝剂异常为0.86 _ 0.05。这两个比率都等于统一的大约2.7_偏差，并且在低能量电子中微子和几米的短基线基准的情况下都观察到了两个异常。 LSND实验是在30 m的基线上进行的，其能量范围为20-53 MeV。观察到的事件数对应于3.8 _的过剩。小型实验的基线为540 m，梁能量为700 meV。实验是用若恩中微子和若恩抗中性替氏菌的Abeam进行的。观察到3.4_和2.8_的事件过剩。这些结果可以通过至少一种额外的中性抑制剂和质量分裂的振荡来解释。这个第四个中微子状态可以解释为星号中微子（与主动中微子相反。与主动中微子不同，静脉内氨酸酯只能通过重力而不是弱相互作用相互作用。由于这种情况，sterileneutrino不会对速率有所帮助Z玻色子的衰变，通过检测器时不会产生任何信号。简短的基线中微子（SBN）程序旨在通过确定是否存在无菌中微子来解决实验结果中的异常。液体氩时间投影室（LARTPC）；在检测器（SBND）附近的较短基线，三个检测器分别沿着110 m，470 m和600 m的Boosterneutrino束中微子光束来源。BNB最初由接近100％的μ子中微子组成，并且该程序的主要目标之一是寻找E外观和消失，作为近检测器，SBNDWILL测量了BNB的无疑风味含量准确的特征。在此方面，SBND与光束源的紧密距离允许测量多个中型Argon的相互作用，因此，在如此庞大的数据样本中，对这些相互作用的研究将对新的精度进行新水平进行。微酮检测器故意将其定位在其前身小型探测器上，并试图复制那里发生的事件的过剩。 ICARUS探测器将集中于测量横梁和SBND的结果的横梁和风味含量，以确定数据中的任何差异是否可能是无菌中微子的结果。LARTPC允许记录粒子轨迹和相互作用的图像和相互作用。在SBN的情况下，这种情况发生在检测器中中微子相互作用并产生颗粒时发生。如果产生的颗粒被充电，它们将又会产生电离轨道，但是如果它们是中性的，它们将通过检测器untice传播