Observation of Shadowing in the Underground Muon Flux in MINOS
1
E. W. Grashorn, for the MINOS Collaboration Observation of Shadowing in the Underground Muon Flux in MINOS This poster was supported directly by the U.S. Department of Energy. MINOS is supported by the U.S. Department of Energy and National Science Foundation, the U.K. Particle Physics and Astronomy Research Council, and the State and University of Minnesota. To capture an astronomical shadow: •Eliminate data taken during times of detector problems (electronics, timing, calibration) •Eliminate muon tracks with poor pointing and resolution (reconstruction, etc.) •Find the location of the body using JPL’s Horizon’s database •Use the Haversine formula to find the 1-D separation of a particular muon from the body, ( taking curvature into account. •Normalize each bin by the solid angle annulus given by the particular angular separation, according to: i 2i-1)S bin where S bin = the square of bin size (0.01 deg 2 ). Fardetector:com pleted July 2003 Field Coil PM Ts& Electronics To Ferm ilab Veto shield Optical Readout 8m wide Far Detector Depth – 2070 m.w.e. (700 m) Size – 5400 ton mass, 486 8 m diameter octagons, 31.5 m long. Every plane is fully instrumented. Passive Detector – Steel, for neutrino interactions and structural stability Active Detector – Scintillating plastic Cosmic Rays – 0.5 Hz cosmic ray rate. The Far Detector is a useful cosmic ray detector because of its size and depth. Magnetic Field – 1.5 T toroidal field allows charge sign determination for CPT studies, etc. Special Thanks M. Kordosky Summary •The 1-D moon shadow has been found with 99.99% confidence •The 1-D sun shadow has been found with 99.9% confidence •The 1-D moon shadow was used to find the resolution of the Far Detector, 0.34 ± 0.07 o •The method to see the sun and moon shadows separately for positive and negative muons was developed. •The method for the 2-D moon shadow was developed. •For more information see the proceedings paper for this poster. eff T Astronomical shadowing Optical astronomers use a catalogue of standard stars to calibrate their new instruments. Though there are no known cosmic ray sources, the sun and the moon are large enough to block a significant number of cosmic ray primaries and act as a calibration “standard sink”. They are close enough that the primaries that pass around each object aren’t bent back into its path by interplanetary magnetic fields nor the geomagnetic field. Since the moon’s location is well known, it can be used to find the absolute pointing and resolution of a particle detector. 1-D moon shadow The plot at left is the one dimensional moon shadow, made using 20 million muons. The dashed red line is the Monte Carlo background and the solid curve is a Gaussian fit of form: where is the average differential muon flux, accounts for smearing from detector resolution, etc., and R m = 0.26, the angular radius of the moon. The fit /ndof = 37.9/38, an improvement of 16.4 over the linear fit (54.3/39 a 10 -4 chance probability) has parameters = 483.9 ±3.1 and = 0.34 ± 0.07. ) ) / ( 1 ( 2 2 / 2 2 e R N m 1-D sun shadow The plot at left is the one dimensional sun shadow. The dashed red line is the Monte Carlo background and the solid curve is a Gaussian fit. The fit /ndof = 40.3/38, an improvement of 8.2 over the liner fit (48.5/39 a 10 -3 chance probability) has parameters = 374.3 ±2.8 and = 0.4 ± 0.09. The sun shadow is less significant than the moon because the sun is further away, allowing solar and interplanetary magnetic fields more time to bend muons back into the sun’s path. Charge separated In order to determine charge sign accurately, a cut on how well the reconstruction determined the momentum is required. This reduced the charge separated sample to 4.6 million muons, 2.7 positive and 1.9 negative. The plots at right are the charge separated one dimensional moon (top) and sun (bottom) shadow. The black triangles are positive, the red circles are negative, the dashed curve is the Gaussian fit, and the solid curve is the linear fit. The Gaussian fit offers little improvement over the linear fit for this sample because of such low statistics. The charge ratio for each distribution is 1.3. Log-likelihood analysis method Create a template of the expected shadow, using the known scattering of dimuons to simulate the effects of muons propagating through rock that affect shadowing. Compare the expected shape of the moon shadow centered at each 0.1 o bin in and RA·cos to the observed data. Sum over all bins in the shadow template: Compare this sum to the no shadow hypothesis See where the greatest deficit exists. This will give the absolute pointing of the detector by finding the most likely deficit in caused by the moon. This analysis is in progress; the method has been established and a result is forthcoming. moon template bin n i th i obs i obs i obs i th i s N N N N N I y x 1 ln 2 ) , , ( s I y x y x , , 0 , , Special Thanks B.Bock, A. Habig
description
Observation of Shadowing in the Underground Muon Flux in MINOS. Far Detector Depth – 2070 m.w.e. (700 m) Size – 5400 ton mass, 486 8 m diameter octagons, 31.5 m long. Every plane is fully instrumented. Passive Detector – Steel, for neutrino interactions and structural stability - PowerPoint PPT Presentation
Transcript of Observation of Shadowing in the Underground Muon Flux in MINOS
E W Grashorn forthe MINOS Collaboration
Observation of Shadowing in the Underground Muon Flux in MINOS
This poster was supported directly by the US Department of Energy MINOS is supported by the US Department of Energy and National Science Foundation the UK Particle Physics and Astronomy Research Council and the State and University of Minnesota
To capture an astronomical shadowbullEliminate data taken during times of detector problems (electronics timing calibration)bullEliminate muon tracks with poor pointing and resolution (reconstruction etc)bullFind the location of the body using JPLrsquos Horizonrsquos databasebullUse the Haversine formula to find the 1-D separation of a particular muon from the body (taking curvature into accountbullNormalize each bin by the solid angle annulus given by the particular angular separation according to i2i-1)Sbinwhere Sbin = the square of bin size (001 deg2)
Far detector completed July 2003
Field Coil PMTs amp Electronics
To Fermilab
Veto shield
Optical Readout
8m wide
Far DetectorDepth ndash 2070 mwe (700 m)
Size ndash 5400 ton mass 486 8 m diameter octagons 315 m long Every plane is fully instrumented
Passive Detector ndash Steel for neutrino interactions and structural stability
Active Detector ndash Scintillating plastic
Cosmic Rays ndash 05 Hz cosmic ray rate The Far Detector is a useful cosmic ray detector because of its size and depth
Magnetic Field ndash 15 T toroidal field allows charge sign determination for CPT studies etc
Special Thanks M Kordosky
SummarybullThe 1-D moon shadow has been found with 9999 confidencebullThe 1-D sun shadow has been found with 999 confidence bullThe 1-D moon shadow was used to find the resolution of the Far Detector 034 plusmn 007o
bullThe method to see the sun and moon shadows separately for positive and negative muons was developedbullThe method for the 2-D moon shadow was developedbullFor more information see the proceedings paper for this poster
effT
Astronomical shadowingOptical astronomers use a catalogue of standard stars to calibrate their new instruments Though there are no known cosmic ray sources the sun and the moon are large enough to block a significant number of cosmic ray primaries and act as a calibration ldquostandard sinkrdquo They are close enough that the primaries that pass around each object arenrsquot bent back into its path by interplanetary magnetic fields nor the geomagnetic field Since the moonrsquos location is well known it can be used to find the absolute pointing and resolution of a particle detector
1-D moon shadowThe plot at left is the one dimensional moon shadow made using 20 million muons The dashed red line is the Monte Carlo background and the solid curve is a Gaussian fit of form
where is the average differential muon flux accounts for smearing from detector resolution etc and Rm = 026 the angular radius of the moon The fit ndof = 37938 an improvement of 164 over the linear fit (54339 a 10-4 chance probability) has parameters = 4839 plusmn31 and = 034 plusmn 007
))(1(2222
eRN
m
1-D sun shadowThe plot at left is the one dimensional sun shadow The dashed red line is the Monte Carlo background and the solid curve is a Gaussian fit The fit ndof = 40338 an improvement of 82 over the liner fit (48539 a 10-3 chance probability) has parameters = 3743 plusmn28 and = 04 plusmn 009 The sun shadow is less significant than the moon because the sun is further away allowing solar and interplanetary magnetic fields more time to bend muons back into the sunrsquos path
Charge separatedIn order to determine charge sign accurately a cut on how well the reconstruction determined the momentum is required This reduced the charge separated sample to 46 million muons 27 positive and 19 negative The plots at right are the charge separated one dimensional moon (top) and sun (bottom) shadow The black triangles are positive the red circles are negative the dashed curve is the Gaussian fit and the solid curve is the linear fit The Gaussian fit offers little improvement over the linear fit for this sample because of such low statistics The charge ratio for each distribution is 13
Log-likelihood analysis methodCreate a template of the expected shadow using the known scattering of dimuons to simulate the effects of muons propagating through rock that affect shadowing Compare the expected shape of the moon shadow centered at each 01o bin in and RAcos to the observed data Sum over all bins in the shadow template
Compare this sum to the no shadow hypothesis
See where the greatest deficit exists This will give the absolute pointing of the detector by finding the most likely deficit in caused by the moon This analysis is in progress the method has been established and a result is forthcoming
moon template
binn
ithi
obsiobs
iobsi
this N
NNNNIyx
1
ln2)(
sIyxyx 0
Special Thanks BBock A Habig
