arXiv subjects

Richard Gran

Publications and source records attributed to Richard Gran.

8 recordsLinked to original sources

arXiv2017

Model uncertainties for Valencia RPA effect for MINERvA

This technical note describes the application of the Valencia RPA multi-nucleon effect and its uncertainty to QE reactions from the GENIE neutrino event generator. The analysis of MINERvA neutrino data in Rodrigues et al. PRL 116 071802 (2016) paper makes clear the need for an RPA suppression, especially at very low momentum and energy transfer. That published analysis does not constrain the magnitude of the effect; it only tests models with and without the effect against the data. Other MINERvA analyses need an expression of the model uncertainty in the RPA effect. A well-described uncertainty can be used for systematics for unfolding, for model errors in the analysis of non-QE samples, and as input for fitting exercises for model testing or constraining backgrounds. This prescription takes uncertainties on the parameters in the Valencia RPA model and adds a (not-as-tight) constraint from muon capture data. For MINERvA we apply it as a 2D ($q_0$,$q_3$) weight to GENIE events, in lieu of generating a full beyond-Fermi-gas quasielastic events. Because it is a weight, it can be applied to the generated and fully Geant4 simulated events used in analysis without a special GENIE sample. For some limited uses, it could be cast as a 1D $Q^2$ weight without much trouble. This procedure is a suitable starting point for NOvA and DUNE where the energy dependence is modest, but probably not adequate for T2K or MicroBooNE.

hep-ex↗

arXiv2016

Deuterium target data for precision neutrino-nucleus cross sections

Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, $F_A(q^2)$, which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of $F_A$ from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of $F_A$. A complete error budget for the nucleon isovector axial radius leads to $r_A^2=0.46(22) \,{\rm fm}^2$, with a much larger uncertainty than determined in the original analyses. The quasielastic neutrino-neutron cross section is determined as $σ(ν_μn \to μ^- p)\big|_{E_ν=1\,{\rm GeV}} = 10.1(0.9) \times 10^{-39}{\rm cm}^2$. The propagation of nucleon-level constraints and uncertainties to nuclear cross sections is illustrated using MINERvA data and the GENIE event generator. These techniques can be readily extended to other amplitudes and processes.

hep-ph↗

arXiv2007

Progress in measuring neutrino quasielastic interactions

This is an exciting time for folks who are looking at neutrino cross sections, and the especially important quasielastic interaction. We are able to inspect several recent results from K2K and MiniBooNE and are looking forward to a couple more high statistics measurements of neutrino and anti-neutrino interactions. There is additional interest because of the need for this cross section information for current and upcoming neutrino oscillation experiments. This paper is a brief review of our current understanding and some puzzles when we compare the recent results with past measurements. I articulate some of the short term challenges facing experimentalists, neutrino event generators, and theoretical work on the quasielastic interaction.

hep-ex↗

arXiv2007

The MINERvA Neutrino Interaction Experiment

The MINERvA neutrino interaction experiment in the NuMI beam at Fermilab will measure several aspects of neutrino interactions in the few GeV energy region. We will make cross section and form factor measurements using a fine-grained fully active scintillator (CH) target, and also investigate nuclear effects on neutrino interactions as well as hadron rescattering using integral nuclear targets made of helium, carbon, iron, and lead. We will improve or add to existing measurements and address some specific questions that are important for current and upcoming neutrino oscillation experiments. This paper reports on the progress toward the design, construction, and calibration of the detector, which we expect will get its first neutrino beam in 2009.

hep-ex↗

arXiv2003

WALTA school-network cosmic ray detectors

The Washington Area Large-scale Time coincidence Array (WALTA) is placing particle detector arrays in secondary schools in the Seattle area to build up a large-scale ultra-high energy cosmic ray detector network, one of several such projects around the world. Scintillation counters salvaged from the CASA experiment in cooperation with the CROP group at the University of Nebraska at Lincoln are refurbished by teachers and students, tested, calibrated, and installed in four-fold arrays at high school sites. To identify time coincidences, a GPS time synchronization system is employed. Data are acquired using a custom lowcost data acquisition card. Here we will describe the logistics of WALTA and show samples of data taken with a prototype array at the University of Washington.

physics.ins-det↗

arXiv2003

GPS Time Synchronization in School-Network Cosmic Ray Detectors

The QuarkNet DAQ card for school-network cosmic ray detectors provides a low-cost alternative to using standard particle and nuclear physics fast pulse electronics modules. Individual detector stations, each consisting of 4 scintillation counter modules, front-end electronics, and a GPS receiver, produce a stream of data in form of ASCII text strings in identifiable set of formats for different functions. The card includes a low-cost GPS receiver module, which permits timestamping event triggers to about 50 nanosecond accuracy in UTC between widely separated sites. The technique used for obtaining precise GPS time employs the 1PPS signal, which is not normally available to users of the commercial GPS module. We had the stock model slightly custom-modified to access this signal. The method for deriving time values was adapted from methods developed for the K2K long-baseline neutrino experiment. Performance of the low-cost GPS module used is compared to that of a more expensive unit with known quality.

physics.ins-det↗

arXiv2003

LabView Interface for School-Network DAQ Card

A low-cost DAQ card has been developed for school-network cosmic ray detector projects, providing digitized data from photomultiplier tubes via a standard serial interface. To facilitate analysis of these data and to provide students with a starting point for custom readout systems, a model interface has been developed using the National Instruments LabVIEW(R) system. This user-friendly interface allows one to initialize the trigger coincidence conditions for data-taking runs and to monitor incoming or pre-recorded data sets with updating singles- and coincidence-rate plots and other user-selectable histograms.

physics.ins-det↗

arXiv2003

Low-Cost Data Acquisition Card for School-Network Cosmic Ray Detectors

The Cosmic Ray Observatory Project (CROP) at University of Nebraska/Lincoln and the Washington Area Large-scale Time coincidence Array (WALTA) at University of Washington/Seattle are among several outreach projects siting cosmic-ray detectors at local high schools in cities around North America, to study the origins and interactions of high-energy cosmic rays. In a collaboration between QuarkNet, the outreach program based at Fermilab, CROP, and WALTA, a low-cost data acquisition electronics card has been developed to collect and synchronize the data from each detector site. The cost for each card is under US$500 for parts, functionally replacing much more expensive electronics crates and modules at each high school site. The card has 4 analog discriminator inputs for photo-multiplier tube signals, a 4-channel Time-to-Digital converter for local coincidence and time-over-threshold measurements at 0.75 ns resolution, programmable trigger logic via a CPLD and microcontroller, and a built-in low-cost GPS receiver/antenna module (via external cable) to provide event trigger time stamps at better than 100 ns accuracy. Temperature sensors and a barometer are also integrated to record environmental data along with the counter data. The card connects to any PC or laptop via a standard RS-232 serial port for data output and control. The microcontroller and CPLD are field programmable and therefore make the card functionality flexible and easy to upgrade.

physics.ins-det↗