1. 1 Momentum measurements of 2ry particles emitted from neutrino interactions in DONuT experiment B. D. Park Nagoya univ. Emulsion Workshop @Nagaya Dec. 7-9, 2006

2. 2 Introduction 1. Charged particle traversing a material deflected by many small angle scatters The most of this deflection is known as coulomb scattering from nuclei 2. Just 600 tracks were identified in the spectrometer (In DONuT experiment ; 2338 tracks were emitted from 578 neutrino interactions) Ref. The first automated momentum measurement by the angular method in the ECC by G. De Lellis et al (NIM 2003)

3. 3 Test experiment (momentum measurement by angular method) 0.8 & 1.5 GeV/c π- (incident angle 0.1 0.2 and 0.3 rad respectively) Sample brick same type as OPERA ECC brick The number of used plate - 24 plate Measured 1/p distribution were Gaussian with standard deviations of 23% P = 0.7 +0.2 / -0.1 GeV/ c 0.8 GeV/c π-

4. 4 Test experiment Measured 1/p distribution were Gaussian with standard deviations of 31% P = 1.3 +0.6 / -0.3 GeV/ c 1.5 GeV/c π-

5. 5 Criteria of secondary tracks A 578 neutrino interactions were observed in DONuT experiment. B 2ry track emitted from these interactions was defined by the following criteria 1. Tracks should start from a vertex position or next downstream plate of that position. 2. Tracks must be constructed from greater than three segments(as track definition). 3. Impact parameter(IP) is less than 5μm => 2338 tracks were selected from neutrino interactions with these conditions. Can not get the enough information of track for measuring the momentum These tracks were emitted from interactions Decay and secondary interaction observed in downstream (less than pl#10)

6. 6 Ratio(measured tracks/ tried tracks) as a function of angle (Only angular method) ECC200 ECC800 Selected track 522 358 Measured track 386 240 (ΔP/ P < 1) Solid circles indicate tracks that passed through less than 20 plates [ECC200] [ ECC800]

7. 7 (Angular & Coordinate method) We are aware that high momentum tracks were recovered by coordinate method. [ECC200] [ ECC800]

8. 8 In Bulk type (Only coordinate method) The 80% of tracks were measured --  bad alignment, slip and distortion.

9. 9 MCS vs. Spectrometer Comparison measured momentum by MCS with that by Spectrometer X - momentum by MCS Y - momentum by Spectrometer Solid circles indicate the momentum of muon tracks [ECC200] [ECC800]

10. 10 The result in each module (1) (2) Rate: (2) / (1) (3) Rate : (3) / (2) [ Conclusion ] 1. We first tried the momentum measurement of real particle emitted from neutrino interaction by MCS 2. The achievement of these result will make a contribution to future ECC experiments.