N. Saoulidou

The DONUT experiment has analyzed 203 neutrino interactions recorded in nuclear emulsion targets. A decay search has found evidence of four tau neutrino interactions with an estimated background of 0.34 events. This number is consistent with the Standard Model expectation.

The DONuT experiment collected data in 1997 and published first results in 2000 based on four observed $\nu_\tau$ charged-current (CC) interactions. The final analysis of the data collected in the experiment is presented in this paper, based on $3.6 \times 10^{17}$ protons on target using the 800 GeV Tevatron beam at Fermilab. The number of observed $\nu_\tau$ CC interactions is 9, from a total of 578 observed neutrino interactions. We calculated the energy-independent part of the tau-neutrino CC cross section ($\nu + \bar \nu$), relative to the well-known $\nu_e$ and $\nu_\mu$ cross sections. The ratio $\sigma(\nu_\tau)$/$\sigma(\nu_{e,\mu})$ was found to be $1.37\pm0.35\pm0.77$. The $\nu_\tau$ CC cross section was found to be $0.72 \pm 0.24\pm0.36 \times 10^{-38}$ cm$^{2}\rm{GeV}^{-1}$. Both results are in agreement the Standard Model.

The DONUT experiment used an emulsion/counter-hybrid-detector, which succeeded in detecting tau–neutrino charged-current interactions. A new method of emulsion analysis, NETSCAN, was used to locate neutrino events and detect tau decays. It is based on a fully automated emulsion readout system (Ultra Track Selector) developed at Nagoya University. The achieved plate-to-plate alignment accuracy of ∼0.2μm over an area of 2.6mm×2.6mm permitted an efficient and systematic tau decay search using emulsion data. Moreover, this accuracy allowed measurement of particle momenta by multiple Coulomb scattering, and contributed to the efficient background rejection for the ντ candidates. This paper describes details of our emulsion analysis methods.

We explore the prospects of constraining general non standard interactions involving light mediators through elastic neutrino-electron scattering events at the DUNE Near Detector (ND). We furthermore consider the special cases of light vector mediators in motivated models such as $U(1)_{B-L}$, $U(1)_{L_\mu - L_\tau}$, $E_6$ and left-right symmetry. The present analysis is based on detailed Monte Carlo simulations of the expected DUNE-ND signal taking into account detector resolution effects, realistic backgrounds as well as On-Axis and Off-Axis neutrino spectra. We show that the high intensity neutrino beam available at Fermilab can place competitive constraints surpassing those of low-energy neutrino searches and direct detection dark matter experiments.

Using a neutrino beam in which a ντ component was identified for the first time, the ντ magnetic moment was measured based on a search for an anomalous increase in the number of neutrino–electron interactions. One such event was observed when 2.3 were expected from background processes, giving an upper 90% confidence limit on μντ of 3.9×10−7μB.

This report provides the results of an extensive and important study of the potential for a U.S. scientific program that will extend our knowledge of neutrino oscillations well beyond what can be anticipated from ongoing and planned experiments worldwide. The program examined here has the potential to provide the U.S. particle physics community with world leading experimental capability in this intensely interesting and active field of fundamental research. Furthermore, this capability is not likely to be challenged anywhere else in the world for at least two decades into the future. The present study was initially commissioned in April 2006 by top research officers of Brookhaven National Laboratory and Fermilab and, as the study evolved, it also provides responses to questions formulated and addressed to the study group by the Neutrino Scientific Advisory Committee (NuSAG) of the U.S. DOE and NSF. The participants in the study, its Charge and history, plus the study results and conclusions are provided in this report and its appendices. A summary of the conclusions is provided in the Executive Summary.

The experimental apparatus used for the first direct observation of the tau neutrino (the DONUT experiment) is described. Its main features consisted of a target system composed of nuclear emulsion targets and scintillation fiber trackers, a magnetic charged-particle spectrometer and detectors for lepton identification. This paper will concentrate on the description of the electronic detectors and their performance in selecting neutrino interactions, making the vertex predictions necessary for locating events in the emulsion target and lepton identification.

We investigate the possible production of a MeV-scale sterile fermion through the up-scattering of neutrinos on nuclei and atomic electrons at different facilities. We consider a phenomenological model that adds a new fermion to the particle content of the Standard Model and we allow for all possible Lorentz-invariant non-derivative interactions (scalar, pseudoscalar, vector, axial-vector and tensor) of neutrinos with electrons and first-generation quarks. We first explore the sensitivity of the DUNE experiment to this scenario, by simulating elastic neutrino-electron scattering events in the near detector. We consider both options of a standard and a tau-optimized neutrino beams, and investigate the impact of a mobile detector that can be moved off-axis with respect to the beam. Next, we infer constraints on the typical coupling, new fermion and mediator masses from elastic neutrino-electron scattering events induced by solar neutrinos in two current dark matter direct detection experiments, XENONnT and LZ. Under the assumption that the new mediators couple also to first-generation quarks, we further set constraints on the up-scattering production of the sterile fermion using coherent elastic neutrino-nucleus scattering data from the COHERENT experiment. Moreover, we set additional constraints assuming that the sterile fermion may decay within the detector. We finally compare our results and discuss how these facilities are sensitive to different regions of the relevant parameter space due to kinematics arguments and can hence provide complementary information on the up-scattering production of a sterile fermion.

We present a method of momentum measurement of charged particles using emulsion data from the DONuT experiment, and report results from the momentum analysis of secondary particles from neutrino interactions. In 578 neutrino interactions, 2338 secondary particles were analyzed and 83.2% of attempted particles were measured by multiple coulomb scattering.

We explore an alternative strategy to determine the neutrino mass hierarchy by making use of possible future neutrino facilities at Fermilab. Here, we use $CPT$-conjugate neutrino channels, exploiting a ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ beam from the NuMI beamline and a ${\overline{\ensuremath{\nu}}}_{e}$ beam from a beta-beam experimental setup. Both experiments are performed at approximately the same $⟨E⟩/L$. We present different possible accelerator scenarios for the beta-beam neutrino setup and fluxes. This $CPT$-conjugate neutrino channel scenario can extract the neutrino mass hierarchy down to ${sin}^{2}2{\ensuremath{\theta}}_{13}\ensuremath{\approx}0.02$.

Particle physics experiments at the intensity frontier aim to probe nature through precision studies of the properties and interactions of its basic constituents, using intense particle beams and innovative detectors. We review the physics potential of several of these experiments, especially those that can be very effectively pursued at Fermilab in the near and intermediate future, assuming that a new intense proton source—Project X—will be available. We concentrate on flavor-violating phenomena that have been identified as the main particle physics drivers for Project X: the study of neutrino masses and mixing through long-baseline neutrino oscillations; searches for rare, flavor-violating muon processes; and precision measurements of kaon decays into neutrinos, [Formula: see text]. We also comment on other opportunities, such as measurements of the anomalous magnetic moment of muon and neutrino-matter scattering.

We are reporting results of the characterization of over 1600 multi-anode R5900-00-M16 photomultipliers manufactured by Hamamatsu Photonics K.K., and installed in the MINOS Far detector. We have conducted extensive tests of the uniformity of gain and collection efficiency of individual anodes, the cross-talk among all 16 channels, the dark noise, and the linearity of response. In our studies we used a blue light-emitting diode to illuminate phototubes through 1.2 mm diameter optical fibers. In this paper, we present summaries of the main characteristics of the tested photomultipliers.

We explore the prospects of constraining general non standard interactions involving light mediators through elastic neutrino-electron scattering events at the DUNE Near Detector (ND). We furthermore consider the special cases of light vector mediators in motivated models such as $U(1)_{B-L}$, $U(1)_{L_μ- L_τ}$, $E_6$ and left-right symmetry. The present analysis is based on detailed Monte Carlo simulations of the expected DUNE-ND signal taking into account detector resolution effects, realistic backgrounds as well as On-Axis and Off-Axis neutrino spectra. We show that the high intensity neutrino beam available at Fermilab can place competitive constraints surpassing those of low-energy neutrino searches and direct detection dark matter experiments.

We will start with a brief overview of neutrino oscillation physics with emphasis on the remaining unanswered questions.Next we will discuss results and status of long baseline accelerator neutrino oscillation experiments that are in a mature data taking mode, have just started or are about to start data taking.Then, we will present the next generation of long baseline experiments with a primary goal to search for the yet to be measured third neutrino mixing angle.Finally we will introduce the plans for future long baseline accelerator neutrino oscillation experiments of which the primary goals are the search for CP violation in the neutrino sector, and the determination of the neutrino mass hierarchy.We will focus on experiments utilizing powerful (0.7 -4.0 MW) neutrino beams, either existing or in the design phase.

This report provides the results of an extensive and important study of the potential for a U.S. scientific program that will extend our knowledge of neutrino oscillations well beyond what can be anticipated from ongoing and planned experiments worldwide. The program examined here has the potential to provide the U.S. particle physics community with world leading experimental capability in this intensely interesting and active field of fundamental research. Furthermore, this capability could be unique compared to anywhere else in the world because of the available beam intensity and baseline distances. The present study was initially commissioned in April 2006 by top research officers of Brookhaven National Laboratory and Fermi National Accelerator Laboratory and, as the study evolved, it also provided responses to questions formulated and addressed to the study group by the Neutrino Scientific Advisory Committee (NuSAG) of the U.S. DOE and NSF. The participants in the study, its Charge and history, plus the study results and conclusions are provided in this report and its appendices. A summary of the conclusions is provided in the Executive Summary.

Within the next ten years the Standard Model will likely have to be modified to encompass a wide range of newly discovered phenomena, new elementary particles, new symmetries, and new dynamics. These phenomena will be revealed through experiment with high energy particle accelerators, mainly the LHC. This will represent a revolution in our understanding of nature, and will either bring us closer to an understanding of all phenomena, through existing ideas such as supersymmetry to superstrings, or will cause us to scramble to find new ideas and a new sense of direction. We are thus entering a dramatic and important time in the quest to understand the fundamental laws of nature and their role in shaping the universe. The energy scales now probed by the Tevatron, of order hundreds of GeV, will soon be subsumed by the LHC and extended up to a few TeV. We expect the unknown structure of the mysterious symmetry breaking of the Standard Model to be revealed. We will then learn the answer to a question that has a fundamental bearing upon our own existence: 'What is the origin of mass?' All modern theories of 'electroweak symmetry breaking' involve many new particles, mainly to provide a 'naturalness' rationale for the weak scale. Supersymmetry (SUSY) represents extra (fermionic) dimensions of space, leading to a doubling of the number of known elementary particles and ushering in many additional new particles and phenomena associated with the various symmetry breaking sectors. The possibility of additional bosonic dimensions of space would likewise usher in an even greater multitude of new states and new phenomena. Alternatively, any new spectroscopy may indicate new principles we have not yet anticipated, and we may see new strong forces and/or a dynamical origin of mass. The wealth of new particles, parameters, CP-phases, and other phenomena carries important implications for precision quark flavor physics experiments that are uniquely sensitive probes of new phenomena. We have already begun to see the enlargement of the Standard Model in the leptonic sector. Neutrino masses and mixing angles, which in the early 1990's were unknown, must now be incorporated into our full description of nature. In a minimal scenario of Majorana masses and mixings amongst the three known left-handed neutrinos, we see a strong hint of a new and very large mass scale, possibly associated with grand unification or the scale of quantum gravity, the Planck mass. We are not yet sure what the proper description of neutrino masses and mixing angles will be. Experiments may reveal additional unexpected particles coupled to the neutrino sector. New phenomena, such as leptonic CP-violation, will be major focal points of our expanding understanding of the lepton sector. There is much to be done with experiment to attack the issues that neutrinos now present. Already, developments in neutrino physics and the possibility of a novel source of CP-violation in the lepton sector have spawned hopes that the cosmic matter-antimatter asymmetry may be explained through leptogenesis. Neutrino physics, together with the search for new energy frontier physics, offers the possibility of experimental handles on the questions of dark matter and dark energy. Without the discovery of new particles in accelerator experiments, the telescope-based cosmological observations of the early universe would remain unexplained puzzles. The process of understanding the laws of physics in greater detail through accelerator-based high energy physics will potentially have incisive impact on our understanding of dark matter and dark energy. Precision flavor physics in both the quark and the lepton sectors offers a window on the sensitive entanglement of beyond-the-Standard-Model physics with rare processes, through quantum loop effects involving known or new states. Flavor physics offers sensitive indirect probes and may be the first place to reveal additional key components of the post-Standard Model physics. The main arenas for quark flavor physics include strange, charm and beauty, hence kaons, D-mesons, B-mesons and heavy baryons. A remarkable historical paradigm for the importance of flavor physics is the well known suppression of flavor-changing neutral currents. The analysis of the K{sub L}-K{sub S} mass difference by Gaillard and Lee, 35 years ago in the Fermilab Theory Group, led to the confirmation of the GIM mechanism and predicted the mass of the charm quark, m{sub c} {approx} 1.5 GeV, definitively and prior to its discovery. This, today, implies an astonishing constraint on SUSY models, e.g., that the down and strange squarks are mass degenerate to 1:10{sup 5}. This, in turn, has spawned a new working hypothesis called 'Minimal Flavor Violation' (MFV). But is MFV really a true principle operating in nature and, if so, where does it come from? Such questions can only be addressed in precision flavor physics experiments.

We request to use the Fermilab NuMI neutrino beam in the MINOS Near Detector Hall to produce neutrino interactions in two separate detector arrangements using prototype target bricks designed for the OPERA experiment. OPERA is scheduled to to begin taking data in the CERN Neutrinos to Gran Sasso (CNGS) beam in 2006. The proposed test set up would be located just upstream of the MINOS Near Detector. The data will be used to validate the OPERA analysis scheme and to study backward particle production in neutrino interactions, which is of interest to the OPERA collaboration as well as the neutrino community in general. In addition, we contend that the data taken in this exposure may also be useful to the MINOS collaboration as additional input to the understanding of the initial composition of the neutrino beam. Ideally, this exposure could take place in early to mid-2005, providing timely feedback to both the OPERA and MINOS collaborations.

We will start with a brief overview of neutrino oscillation physics with emphasis on the remaining unanswered questions. Next, after mentioning near future reactor and accelerator experiments searching for a non zero {theta}{sub 13}, we will introduce the plans for the next generation of long-baseline accelerator neutrino oscillation experiments. We will focus on experiments utilizing powerful (0.7-2.1 MW) Fermilab neutrino beams, either existing or in the design phase.

• The "Ultimate'' goals in neutrino oscillation physics..... V• The "Ingredients" needed in order to achieve the"Ultimate" goals.• A phased neutrino oscillation program at Fermilab withProject X• Summary / Conclusions

Neutrino Energy (GeV)

Neutrino oscillations provide the first evidence for physics beyond the Standard Model. I will briefly overview the neutrino hi-story, describing key discoveries over the past decades that shaped our understanding of neutrinos and their behavior. Fermilab was, is and hopefully will be at the forefront of the accelerator neutrino experiments. NuMI, the most powerful accelerator neutrino beam in the world has ushered us into the era of precise measurements. Its further upgrades may give a chance to tackle the remaining mysteries of the neutrino mass hierarchy and possible CP violation.

We present a novel calorimeter concept capable of achieving energy resolution better than 25%/radicE for single hadrons and jets. The energy resolution improvement is achieved by utilizing the Cerenkov photon signal as an estimator of the energy loss due to nuclear processes. We demonstrate the excellent energy resolution for the case of a large homogeneous calorimeter by GEANT4 simulation. We also investigate a possible design of a sampling calorimeter involving alternating lead glass and scintillator planes. This design enables construction of a calorimeter with arbitrary segmentation in the transverse direction and in depth, as is required by many high-energy physics experiments. Such a calorimeter would at the same time enable excellent energy resolution for electrons and photons.