Petit-exposure at neutrino beamline (PEANUT)

Niwa, K. ; U., /Nagoya

Fermi National Accelerator Laboratory

关键词: Electrons;    Plastics;    Decay;    Nuclear Emulsions;    Cern;   

DOI  :  10.2172/912643
RP-ID  :  FERMILAB-TEST-0952
RP-ID  :  AC02-07CH11359
RP-ID  :  912643

美国|英语

来源: UNT Digital Library

【 摘 要 】

The advantages of using nuclear emulsion as a particle detector are well known. The high resolution of emulsion has made it a medium of choice for a number of applications where the required spatial and angular resolution are paramount and its limitations due to the lack of timing information are less important. Emulsions are commonly used as cosmic ray detectors and have found applications in high energy experiments for detecting short lived particles such as charm, beauty and tau. The addition of electronic detectors to emulsion experiments solved the problem of the lack of timing information in the emulsion, but it was the development of automatic scanning machines that revolutionized the use of these hybrid detectors, making them capable of performing even in high rate environments. Most recently, The DONuT experiment (FNAL-E872), used a hybrid emulsion spectrometer to make the first direct observation of tau neutrino interactions [1]. The CNGS facility is being constructed to deliver a {nu}{sub {mu}} beam from the CERN SPS to the Gran Sasso Laboratory. Since it is believed that {nu}{sub {mu}} {leftrightarrow} {nu}{sub {tau}} oscillations explain the observed atmospheric {nu}{sub {mu}} deficit, the CNGS beam, coupled with a detector capable of observing {tau} appearance is an important experiment in the context of the world wide effort to determine the neutrino mass mixing matrix. The OPERA detector has been optimized to detect a significant sample of {nu}{sub {tau}} interactions by the subsequent observation of {tau} production and decay [2]. The OPERA target is a massive emulsion detector made in a sandwich structure of lead plates and layers of nuclear emulsion. For historical reasons this arrangement has been called an Emulsion Cloud Chamber or ECC. The ECC concept, which has many advantages over the use of bulk emulsion, has been used in the DONuT experiment. The ECC detector is capable of measuring all of the tracks, not due to nuclear fragments, coming from the primary neutrino interaction vertex, with their three dimensional slopes and momenta. It is also capable of electron identification with good e/{gamma} separation, due to its very fine segmentation. The OPERA ECC target modules are constructed as bricks of dimensions 12.5 x 10.0 x 7.5 cm{sup 3} in horizontal, vertical and along the beam axis. Each brick consists of series of 56 (1 mm thick) plates of passive material (lead or iron) alternated with emulsion films (43 {micro}m emulsion layer on both sides of a transparent 200 {micro}m thick plastic film). In preparation for OPERA we would like to expose the OPERA target modules to a beam of neutrinos. This will allow us to test many of our analysis procedures and techniques as well as to validate the simulation of neutrino interactions, both for the production of forward and backward particles. Although the HE (high energy) beam of NuMI would be a better match to the CNGS energy, data acquired with NuMI LE (low energy) beam would serve the same purpose, albeit more challenging. Given the high interaction rate from the NuMI beam, the test detector target mass can be kept low and additional detectors can easily be built around a small target. These measurements are not possible in the CNGS beam, since it has no short baseline hall.