A precision measurement of nu _mu disappearance in the T2K experiment
<p>T2K is a long-baseline accelerator neutrino oscillation experiment using the high-intensity ν<sub>μ</sub> beam produced at J-PARC. Sitting 295 km away, the giant Super-Kamiokande detector, a 50 kt water tank instrumented with 11,129 photosensitive detectors, sees a narrow band b...
| Main Authors: | , |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
2014
|
| Subjects: |
| _version_ | 1817931779481272320 |
|---|---|
| author | Dealtry, T Thomas James Dealtry |
| author2 | Andreopoulos, C |
| author_facet | Andreopoulos, C Dealtry, T Thomas James Dealtry |
| author_sort | Dealtry, T |
| collection | OXFORD |
| description | <p>T2K is a long-baseline accelerator neutrino oscillation experiment using the high-intensity ν<sub>μ</sub> beam produced at J-PARC. Sitting 295 km away, the giant Super-Kamiokande detector, a 50 kt water tank instrumented with 11,129 photosensitive detectors, sees a narrow band beam peaked at 600 MeV. The baseline to energy ratio is finely tuned for studying neutrino oscillations at the atmospheric neutrino squared-mass splitting. The beam is also sampled 280m downstream of the neutrino production target by a series of finely segmented solid scintillator and time projection chamber detectors. Observing changes in the neutrino beam between the two detectors allows oscillation parameters to be accurately extracted.</p> <p>A ν<sub>μ</sub>-disappearance analysis was performed on the combined T2K Run 1+2+3+4 dataset, corresponding to integrated J-PARC neutrino beam exposure of 6.57x10<sup>20</sup> POT, in a framework of three active neutrino flavour oscillations including matter effects in constant-density matter. The observed reconstructed energy spectrum of 1 μ-like ring events was fitted, and separate fits were made for the normal and the inverted mass hierarchies. In these fits, sin<sup>2</sup> θ<sub>23</sub> and either |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">32</sub>| (normal mass hierarchy) or |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">31</sub>| (inverted mass hierarchy) were allowed to float. The oscillation parameters sin<sup>2</sup> θ<sub>13</sub>, sin<sup>2</sup> θ<sub>12</sub>, Δ<em>m</em><sup>2</sup> <sub style="position: relative; left: -.7em;">21</sub>, δ<sub><em>CP</em></sub> , and all 41 systematic parameters considered in this analysis were also allowed to float in the fit.</p> <p>This analysis predicts 445.98±23.46(syst) 1 μ-like ring events in SK in the absence of any oscillation, but only 120 were observed. The observed deficit has a strong energy dependence; the ratio of observed to expected, under the no-oscillation hypothesis, is ∼26% < 0.5 GeV, ∼10% between 0.5 and 1 GeV and ∼72% > 1 GeV.</p> <p>The 68% confidence intervals on the oscillation parameters can be summarised as sin<sup>2</sup> θ<sub>23</sub> = 0.514 <sup>+0:049</sup> <sub style="position: relative; left: -3em;">-0:050</sub> |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">32</sub>| = 2.51±0.10 eV<sup>2</sup>⁄c<sup>4</sup> for the normal mass hierarchy, and sin<sup>2</sup> θ<sub>23</sub> = 0.511 <sup>+0:050</sup> <sub style="position: relative; left: -3em;">-0:049</sub> |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">31</sub>| = 2.48±0.10 eV<sup>2</sup>⁄c<sup>4</sup> for the inverted mass hierarchy. This is the most precise measurement of sin<sup>2</sup> θ<sub>23</sub> to date.</p> |
| first_indexed | 2024-03-06T18:21:48Z |
| format | Thesis |
| id | oxford-uuid:068b393a-7736-43d8-b4f4-60f2ced57349 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:27:27Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | oxford-uuid:068b393a-7736-43d8-b4f4-60f2ced573492024-12-01T10:20:51ZA precision measurement of nu _mu disappearance in the T2K experimentThesishttp://purl.org/coar/resource_type/c_db06uuid:068b393a-7736-43d8-b4f4-60f2ced57349PhysicsEnglishOxford University Research Archive - Valet2014Dealtry, TThomas James DealtryAndreopoulos, CWeber, A<p>T2K is a long-baseline accelerator neutrino oscillation experiment using the high-intensity ν<sub>μ</sub> beam produced at J-PARC. Sitting 295 km away, the giant Super-Kamiokande detector, a 50 kt water tank instrumented with 11,129 photosensitive detectors, sees a narrow band beam peaked at 600 MeV. The baseline to energy ratio is finely tuned for studying neutrino oscillations at the atmospheric neutrino squared-mass splitting. The beam is also sampled 280m downstream of the neutrino production target by a series of finely segmented solid scintillator and time projection chamber detectors. Observing changes in the neutrino beam between the two detectors allows oscillation parameters to be accurately extracted.</p> <p>A ν<sub>μ</sub>-disappearance analysis was performed on the combined T2K Run 1+2+3+4 dataset, corresponding to integrated J-PARC neutrino beam exposure of 6.57x10<sup>20</sup> POT, in a framework of three active neutrino flavour oscillations including matter effects in constant-density matter. The observed reconstructed energy spectrum of 1 μ-like ring events was fitted, and separate fits were made for the normal and the inverted mass hierarchies. In these fits, sin<sup>2</sup> θ<sub>23</sub> and either |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">32</sub>| (normal mass hierarchy) or |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">31</sub>| (inverted mass hierarchy) were allowed to float. The oscillation parameters sin<sup>2</sup> θ<sub>13</sub>, sin<sup>2</sup> θ<sub>12</sub>, Δ<em>m</em><sup>2</sup> <sub style="position: relative; left: -.7em;">21</sub>, δ<sub><em>CP</em></sub> , and all 41 systematic parameters considered in this analysis were also allowed to float in the fit.</p> <p>This analysis predicts 445.98±23.46(syst) 1 μ-like ring events in SK in the absence of any oscillation, but only 120 were observed. The observed deficit has a strong energy dependence; the ratio of observed to expected, under the no-oscillation hypothesis, is ∼26% < 0.5 GeV, ∼10% between 0.5 and 1 GeV and ∼72% > 1 GeV.</p> <p>The 68% confidence intervals on the oscillation parameters can be summarised as sin<sup>2</sup> θ<sub>23</sub> = 0.514 <sup>+0:049</sup> <sub style="position: relative; left: -3em;">-0:050</sub> |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">32</sub>| = 2.51±0.10 eV<sup>2</sup>⁄c<sup>4</sup> for the normal mass hierarchy, and sin<sup>2</sup> θ<sub>23</sub> = 0.511 <sup>+0:050</sup> <sub style="position: relative; left: -3em;">-0:049</sub> |Δ<em>m</em><sup>2</sup><sub <sub="" style="position: relative; left: -.5em;">31</sub>| = 2.48±0.10 eV<sup>2</sup>⁄c<sup>4</sup> for the inverted mass hierarchy. This is the most precise measurement of sin<sup>2</sup> θ<sub>23</sub> to date.</p> |
| spellingShingle | Physics Dealtry, T Thomas James Dealtry A precision measurement of nu _mu disappearance in the T2K experiment |
| title | A precision measurement of nu _mu disappearance in the T2K experiment |
| title_full | A precision measurement of nu _mu disappearance in the T2K experiment |
| title_fullStr | A precision measurement of nu _mu disappearance in the T2K experiment |
| title_full_unstemmed | A precision measurement of nu _mu disappearance in the T2K experiment |
| title_short | A precision measurement of nu _mu disappearance in the T2K experiment |
| title_sort | precision measurement of nu mu disappearance in the t2k experiment |
| topic | Physics |
| work_keys_str_mv | AT dealtryt aprecisionmeasurementofnumudisappearanceinthet2kexperiment AT thomasjamesdealtry aprecisionmeasurementofnumudisappearanceinthet2kexperiment AT dealtryt precisionmeasurementofnumudisappearanceinthet2kexperiment AT thomasjamesdealtry precisionmeasurementofnumudisappearanceinthet2kexperiment |