190 likes | 328 Views
CsI calibration using pi0 's produced by neutron-nucleus interaction ( KEK-PS E391a experiment ). S. Y. Lee Pusan National University. E391a Collaboration. High Energy Accelerator Research Organization, KEK Faculty of Science and Engineering, Saga University
E N D
CsI calibration using pi0 'sproduced by neutron-nucleus interaction( KEK-PS E391a experiment ) S. Y. Lee Pusan National University
E391a Collaboration • High Energy Accelerator Research Organization, KEK • Faculty of Science and Engineering, Saga University • Department of Physics, Yamagata University • Department of Physics, Osaka University • Research Center for Nuclear Physics, Osaka University • National Defense Academy of Japan • Department of Physics, Ibaraki University • Joint Institute for Nuclear Research (Dubna) Russia • Department of Physics, University of Chicago • Fermi National Accelerator Laboratory • Department of Physics, Pusan National University
I. Motivation • KLpo n n • ggNothing • pure CsI calorimeter4pveto system • CALIBRATION to EM Calorimeter
II. Methods invariant mass of p0produced by neutron nucleus interaction at Al target n p0 Pure CsI Arrays
Do i=1, 576 for given CsI Module Reconstruct invariant mass from all 2 g event ( , other) Take mean from the invariant mass distribution Make correction factor ENDDO Update gains by respectively Iterate above process until to get correct invariant mass peak of p0 Iteration Process
(continued) Data Sample according to distance between Target and CsI calorimeter • 3 m : ~ 1.5 M reconstructed events • 7 m : ~ 1.5 M reconstructed events
III. Correction to Incident Position and Angle(by M.C.) 1. Position correction at normal incident Center of gravity(cm) Center of gravity Incident position (cm) Incident position (cm) Before correction After correction
2. Correction to position and angle Center of gravity (cm) X axis : incident position(cm) Y axis : center of gravity(cm) Incident position (cm) Before correction After correction
Before correction After correction 3. Results (position and angular correction) MeV/c2 MeV/c2 = 5.4 MeV/c2 = 4.1 MeV/c2
IV. Iteration MeV/c2 MeV/c2 Before Iteration After Iteration
Before Iteration = 4.1 MeV/c2 RMS of Mass Peak of Each CsIs = 1.05 MeV/c2 ~ 480 MeV/C2 After Iteration = 3.7 MeV/c2 RMS of Mass Peak of Each CsIs = 0.05 MeV/C2 ~ 540 MeV/C2 Results (Iteration)
Gain Change (preliminary) • Before (from muon) mean : 2.3 MeV/pC MeV/pC MeV/pC • After Iteration mean : 2.7 MeV/pC
V. Summary • We improve the precision of CsI Calibration • Position and Angular Corrections More Correct position of Gamma Better reconstructed pi0 mass peak ( 25 % improvement of sigma ) • Iteration Process Additional 10 % improvement Update gain constant Proper mass peak position of p0 and
Differential Angular Correction cog(q=n) - cog(q=n-1) Incident position (cm)
For given CsI module If gain is fully calibrated, Take the ratio ,Assume We can get , Correction Factor
Basic Properties of Pure CsI • : 4.53 • : 1.85 • Moliere : 3.8 • : 5.6 • : 36.5 • : 36f, 620s • : 305f, ~480s • : 1.80 • light output(rel) : 0.10f, 0.20s (4k )f
Mean value distribution( mass peaks of reconstructed pion mass distribution of CsIs) • Before (from muon) RMS : 1.05 MeV/c2 MeV/pC MeV/c2 MeV/c2 • After Iteration RMS : 0.5 MeV/c2
Before correction After correction 3. Results-more = 5.3 MeV/c2 = 4.1 MeV/c2