Measurement of neutrino flux from neutrino-electron elastic scattering

Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently a measurement of this process in an accelerator-based nu(mu) beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to similar to 10% due to uncertainties in hadron production and focusing. We have isolated a sample of 135 +/- 17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI nu(mu) flux from 9% to 6%. Our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies

Measurement of Coherent Production of pi(+/-) in Neutrino and Antineutrino Beams on Carbon from E-upsilon of 1.5 to 20 GeV

Neutrino-induced coherent charged pion production on nuclei upsilon((-))(mu)A -- \u3e mu(+/-)pi(-/+)A is a rare, inelastic interaction in which a small squared four-momentum |t| is transferred to the recoil nucleus, leaving it intact in the reaction. In the scintillator tracker of MINERvA, we remove events with evidence of particles from nuclear breakup and reconstruct |t| from the final-state pion and muon. We select low |t| events to isolate a sample rich in coherent candidates. By selecting low |t| events, we produce a model-independent measurement of the differential cross section for coherent scattering of neutrinos and antineutrinos on carbon. We find poor agreement with the predicted kinematics in neutrino generators used by current oscillation experiments

Cross sections for nu(mu) and (nu)over-bar(mu) induced pion production on hydrocarbon in the few-GeV region using MINERvA

Separate samples of charged-current pion production events representing two semi-inclusive channels nu(mu)-CC(pi(+)) and (nu) over bar (mu) -CC(pi(0)) have been obtained using neutrino and antineutrino exposures of the MINERvA detector. Distributions in kinematic variables based upon mu(+/-)-track reconstructions are analyzed and compared for the two samples. The differential cross sections for muon production angle, muon momentum, and four-momentum transfer Q(2) are reported, and cross sections versus neutrino energy are obtained. Comparisons with predictions of current neutrino event generators are used to clarify the role of the Delta(1232) and higher-mass baryon resonances in CC pion production and to show the importance of pion final-state interactions. For the nu(mu)-CC(pi(+)) [(nu) over bar (mu)-(pi(0))] sample, the absolute data rate is observed to lie below (above) the predictions of some of the event generators by amounts that are typically 1-to- 2 sigma. However the generators are able to reproduce the shapes of the differential cross sections for all kinematic variables of either data set

Identification of Nuclear Effects in Neutrino-Carbon Interactions at Low Three-Momentum Transfer

Two different nuclear-medium effects are isolated using a low three-momentum transfer subsample of neutrino-carbon scattering data from the MINERvA neutrino experiment. The observed hadronic energy in charged-current nu(mu) interactions is combined with muon kinematics to permit separation of the quasielastic and Delta(1232) resonance processes. First, we observe a small cross section at very low energy transfer that matches the expected screening effect of long-range nucleon correlations. Second, additions to the event rate in the kinematic region between the quasielastic and Delta resonance processes are needed to describe the data. The data in this kinematic region also have an enhanced population of multiproton final states. Contributions predicted for scattering from a nucleon pair have both properties; the model tested in this analysis is a significant improvement but does not fully describe the data. We present the results as a double-differential cross section to enable further investigation of nuclear models. Improved description of the effects of the nuclear environment are required by current and future neutrino oscillation experiments

Evidence of Coherent K+ Meson Production in Neutrino-Nucleus Scattering

Neutrino-induced charged-current coherent kaon production nu(mu)A -\u3e mu(-)K(+)A is a rare, inelastic electroweak process that brings a K+ on shell and leaves the target nucleus intact in its ground state. This process is significantly lower in rate than the neutrino-induced charged-current coherent pion production because of Cabibbo suppression and a kinematic suppression due to the larger kaon mass. We search for such events in the scintillator tracker of MINERvA by observing the final state K+, mu(-), and no other detector activity, and by using the kinematics of the final state particles to reconstruct the small momentum transfer to the nucleus, which is a model-independent characteristic of coherent scattering. We find the first experimental evidence for the process at 3 sigma significance

Evidence for Neutral-Current Diffractive pi(0) Production from Hydrogen in Neutrino Interactions on Hydrocarbon

The MINERvA experiment observes an excess of events containing electromagnetic showers relative to the expectation from Monte Carlo simulations in neutral-current neutrino interactions with mean beam energy of 4.5 GeV on a hydrocarbon target. The excess is characterized and found to be consistent with neutral-current pi(0) production with a broad energy distribution peaking at 7 GeV and a total cross section of 0.26 +/- 0.02(stat.) +/- 0.08(sys.) x 10(-39) cm(2). The angular distribution, electromagnetic shower energy, and spatial distribution of the energy depositions of the excess are consistent with expectations from neutrino neutral-current diffractive pi(0) production from hydrogen in the hydrocarbon target. These data comprise the first direct experimental observation and constraint for a reaction that poses an important background process in neutrino-oscillation experiments searching for nu(mu) to nu(e) oscillations

Measurement of Electron Neutrino Quasielastic and Quasielasticlike Scattering on Hydrocarbon at \u3c E-v \u3e=3.6 GeV

The first direct measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon in the few-GeV region of incident neutrino energy has been carried out using the MINERvA detector in the NuMI beam at Fermilab. The flux-integrated differential cross sections in the electron production angle, electron energy, and Q(2) are presented. The ratio of the quasielastic, flux-integrated differential cross section in Q(2) for v(e) with that of similarly selected v(mu)-induced events from the same exposure is used to probe assumptions that underpin conventional treatments of charged-current v(e) interactions used by long-baseline neutrino oscillation experiments. The data are found to be consistent with lepton universality and are well described by the predictions of the neutrino event generator GENIE

Measurement of K+ production in charged-current nu(mu) interactions

Production of K+ mesons in charged-current nu(mu) interactions on plastic scintillator (CH) is measured using MINERvA exposed to the low-energy NuMI beam at Fermilab. Timing information is used to isolate a sample of 885 charged-current events containing a stopping K+ which decays at rest. The differential cross section in K+ kinetic energy, d sigma/dT(K), is observed to be relatively flat between 0 and 500 MeV. Its shape is in good agreement with the prediction by the GENIE neutrino event generator when final-state interactions are included, however the data rate is lower than the prediction by 15%

Drug regulatory-compliant validation of a qPCR assay for bioanalysis studies of a cell therapy product with a special focus on matrix interferences in a wide range of organ tissues

Quantitative polymerase chain reaction (qPCR) has emerged as an important bioanalytical method for assessing the pharmacokinetics of human-cell-based medicinal products after xenotransplantation into immunodeficient mice. A particular challenge in bioanalytical qPCR studies is that the different tissues of the host organism can affect amplification efficiency and amplicon detection to varying degrees, and ignoring these matrix effects can easily cause a significant underestimation of the true number of target cells in a sample. Here, we describe the development and drug regulatory-compliant validation of a TaqMan qPCR assay for the quantification of mesenchymal stromal cells in the range of 125 to 20,000 cells/200 L lysate via the amplification of a human-specific, highly repetitive α-satellite DNA sequence of the chromosome 17 centromere region HSSATA17. An assessment of matrix effects in 14 different mouse tissues and blood revealed a wide range of spike recovery rates across the different tissue types, from 11 to 174%. Based on these observations, we propose performing systematic spike-and-recovery experiments during assay validation and correcting for the effects of the different tissue matrices on cell quantification in subsequent bioanalytical studies by multiplying the back-calculated cell number by tissue-specific factors derived from the inverse of the validated percent recovery rate

Measurement of muon plus proton final states in nu(mu) interactions on hydrocarbon at \u3c E-nu \u3e=4.2 GeV

A study of charged-current muon neutrino scattering on hydrocarbon in which the final state includes a muon, at least one proton, and no pions is presented. Although this signature has the topology of neutrino quasielastic scattering from neutrons, the event sample contains contributions from quasielastic and inelastic processes where pions are absorbed in the nucleus. The analysis accepts events with muon production angles up to 70 degrees and proton kinetic energies greater than 110 MeV. The cross section, when based completely on hadronic kinematics, is well described by a relativistic Fermi gas nuclear model including the neutrino event generator modeling for inelastic processes and particle transportation through the nucleus. This is in contrast to the quasielastic cross section based on muon kinematics, which is best described by an extended model that incorporates multinucleon correlations. This measurement guides the formulation of a complete description of neutrino-nucleus interactions that encompasses the hadronic as well as the leptonic aspects of this process