uta-hep/if-005 lbne beam simulation studies · pdf filelbne beam simulation studies...

UTA-HEP/IF-005

1

LBNE Beam Simulation Studies

UTA-HEP/IF-005

August 19, 2013

Hyun Keun Ahn

High Energy Physics Group

Department of Physics

The University of Texas at Arlington

Abstract

To broaden our understanding of neutrinos, which may answer fundamental questions such

as why universe came to consist of matter rather than antimatter, we must enhance our current

technology to better detect them. This study was conducted to observe the effects of various

factors, such as the decay pipe filling, size of beam, target, and baffle, and the location of the

decay pipe, on flux. To do so, I used LBNE beam simulation software g4lbne. In first part of the

experiment, two different filling materials, Air and Helium, and two distinct physics lists,

QGSP_BERT and FTFP_BERT, were involved. For both physics lists, the results demonstrated

that 12.5% higher muon neutrino fluxes were generated in helium, approximately; on the

contrary, higher antineutrino fluxes were generated in air. Therefore, I concluded that helium is

more suitable filling material for decay pipe than air. After this finding, using helium as the

filling medium, I ran simulations, each with different decay pipe location. The results showed

that farther away the decay pipe is from the MCZERO (upstream end of the horn 1), higher the

muon neutrino flux is; it increased on average of 4% per 20m increase. Moreover, I found out

that after changes have been made with beam width, baffle dimension, and the target width, 4.6%

higher muon neutrino fluxes were generated. This study will help make numerous decisions

about design of ideal working environment for the experiment.

1. Introduction

Neutrinos are the most abundant particles in the universe yet the most difficult to detect,

since they rarely interact with other matter. There are three different kinds: electron neutrino,

muon neutrino, and tau neutrino. Recently, numerous findings, such as presence of dark matter,

have suggested realm of particle physics beyond the Standard model [1], which is governed by

the four fundamental forces and states that neutrinos are massless particles [2]. Understanding of

the neutrinos may provide explanations for numerous exotic physical phenomena.

Fig. 1 Proposed Long-Baseline Neutrino Experiment Setup. Credit: Symmetry Magazine

UTA-HEP/IF-005

2

Long-Baseline Neutrino Experiment (LBNE) is a world-class project to establish both the

experimental facilities and the physics programs that will measure fundamental physical

parameters to high precision, including neutrino mass hierarchy, CP violation, and the value of

the mixing parameter & theta [3]. The experiment will involve high-intensity, 1,300-km baseline

accelerator neutrino beam and an advanced liquid argon TPC far detector [4]. Fermilab’s Main

Injector accelerator will generate protons, which will produce high-intensity neutrino beam that

will collide with a graphite target; the resultant particles, mainly kaons and pions, then will enter

the decay pipe, where they decay into neutrinos. Flux measured at both near detector and far

detector will identify the neutrino oscillations that took place in the decay pipe [5]. The beam

line will be sent from Fermilab to the detector located at Sanford lab in South Dakota.

Major purpose of this report was to identify which material is more ideal for the decay pipe

fillings. In this experiment, air and helium were compared. Then I analyzed effect of varied

decay pipe location and changes in beam width, target width, and baffle radius on flux.

2. Experimental Setup

2.1 LBNE Neutrino Beam Simulation Software g4lbne

G4lbne is software specifically designed for LBNE beam simulation. It incorporates Geant4

geometry and takes Fluka target production Ntuples as an input. To exploit it, you need various

accounts and appropriate working environment.

Primarily, submit online request form to receive FNAL ID, service account, and Kerberos

account; name of supervisor and working institution is required to verify your identity. Once

done, login to Fermilab service desk and request for LBNE account and FNALU account. Then,

properly adjust your local computer to execute “kinit –f [username]@FNAL.GOV” to connect to

FNAL, which allows connecting to the Fermilab computer using “ssh –Y

[username]@lbnegpvm01.fnal.gov” command.

In the Fermilab computer, you have access to data directory and app directory. In the app

directory, you can install the g4lbne software using command. Next, ask one of the LBNE

managers to get read write access to g4lbne. Instruction for LBNE beam simulation setup can be

found in the README.txt file in the g4lbne directory.

2.2 Data Analysis software ROOT

ROOT is an object-oriented program developed by CERN to effectively analyze the outputs

from the high energy physics experiments; it uses C++ language. You can download the ROOT

from the website http://root.cern.ch/drupal/ for operating system you use. Using macros, you can

produce diverse kinds of plots, ranging from scatter plot to histogram; they can be produced in

1D, 2D, and 3D. Moreover, ROOT calculates numerous statistical measures, such as mean, RMS

(root mean square), and kurtosis, with errors. Most importantly, you can perform various

manipulations with histograms. For example, you can fit them using Gaussian functions and

show the fit parameters with errors. Furthermore, you can overlay two or more plots on same

canvas and change the color and shape of them. One of the most convenient features of ROOT is

its capacity to take ratio of plots or take ratio of ratio. These ratio plots are useful in visually

observing how closely two plots overlap or resemble. Detailed information is available in the

ROOT user guide. Thorough scrutiny of data can be achieved with ROOT.

2.3 Fermilab Grid

To get Fermilab Grid permission for the first time, you need to fill out VOMS account form.

Afterwards, use ssh command to login to gpsn01.fnal.gov and then again to lbnegpvm01.

Once done, you can begin submitting jobs in the grid using python script file

‘submit_flux.py’, which is stored in example directory (/lbne/app/users/[username]/lbne-

http://root.cern.ch/drupal/

UTA-HEP/IF-005

3

beamsim/g4lbne/example/). Before submitting, you can choose physics lists to use, input card

files, and set the number of protons on the target and the number of jobs. Possible command line

used for submission of job would look like ‘python submit_flux.py --physics list=FTFP_BERT -i

CD1-CDR_Geo_Helium -n 100000 -f 1 -l 1250.’ In this example, FTFP_BERT is the physics list

used, CD1-CDR_Geo_Helium is the input card file, 100000 is the number of protons on the

target (POT), and 1250 is the number of jobs submitted.

The outputs are stored in /lbne/data/users/[username]/fluxfiles/g4lbne/[input card

file]/[physics list]/nubeam-G4PBeam-stdnubeam/logfiles/. To generate raw histograms for flux

and current event rates (both charged and neutral) for specific physics list and input card file,

first you need to modify them in the ‘eventRates.h” file in the example directory. Then, follow

the steps in the ‘eventRates.C’ to run it in the root session, which will create the file in form of

Ntuples (an ordered list of elements) in your example directory.

3. Data Set

3.1 Flux in Air and Helium and Flux Ratio

I generated diverse flux histograms for both helium and air using both physics lists: muon

neutrino , muon antineutrino ( , electron neutrino (Ve), and electron antineutrino ( .

These plots showed the flux generated throughout the energy level (0.0-20.0 GeV). I used

Sumw2() command in ROOT to create error bars on the histograms. Then, I generated ‘Helium

flux / Air flux’ ratio plots by dividing them. I used Sumw2() command in ROOT to create error

bars on the histograms and IntegralAndError() command to calculate the integrated flux ratio for

4 intervals (0.0-0.5Gev, 0.5-1.5Gev, 1.5-5.0Gev, 5.0-10.0Gev).

3.2 Current event rates in Air and Helium and Current event rates Ratio

I generated diverse current events rate histograms (charged current and neutral) for both

helium and air using both physics lists: muon neutrino , muon antineutrino ( , and

electron neutrino (Ve), and electron antineutrino ( . These plots showed the flux generated

throughout the energy level (0.0-20.0 GeV). I used Sumw2() command in ROOT to create error

bars on the histograms. Then, I generated ‘Helium cceventrate / Air cceventrate’ and ‘Helium

nceventrate / Air nceventrate’ ratio plots by dividing corresponding histograms. I used Sumw2()

command in ROOT to create error bars on the histograms.

3.3 Flux before and after changes in beam width, radius of baffle, and target width and

Flux Ratio

Changes with beam width (decreased to 1.3mm from 1.5mm, radius of baffle (increased to

6.5mm from 5.5mm), and the width of the target (increased to 7.4mm from 6.4mm) were made.

Afterwards, I generated diverse flux histograms before and after changes using FTFP_BERT:

muon neutrino , muon antineutrino ( , electron neutrino (Ve), and electron antineutrino

( . These plots showed the flux generated throughout the energy level (0.0-20.0 GeV). I used

Sumw2() command in ROOT to create error bars on the histograms. Then, I generated ‘primitive

flux / modified flux’ ratio plots by dividing them. I used Sumw2() command in ROOT to create

error bars on the histograms and IntegralAndError() command to calculate the integrated flux

ratio for 4 intervals (0.0-0.5Gev, 0.5-1.5Gev, 1.5-5.0Gev, 5.0-10.0Gev).

3.4 Current event rates before and after changes in beam width, radius of baffle, and

target width and Current event rates Ratio

Changes with beam width (decreased to 1.3mm from 1.5mm, radius of baffle (increased to

6.5mm from 5.5mm), and the width of the target (increased to 7.4mm from 6.4mm) were made.

Afterwards, I generated diverse current event rates histograms (both charged current and neutral)

UTA-HEP/IF-005

4

before and after changes in three parameters (beam width, baffle radius, and target width) was

made using FTFP_BERT: muon neutrino , muon antineutrino ( , electron neutrino (Ve),

and electron antineutrino ( . These plots showed the current event rates throughout the energy

level (0.0-20.0 GeV). I used Sumw2() command in ROOT to create error bars on the histograms.

Then, I generated ‘primitive cceventrate / modified cceventrate’ and ‘primitive nceventrate /

modified nceventrate’ ratio plots by dividing them. I used Sumw2() command in ROOT to create

error bars on the histograms.

3.5 Flux generated at various locations of the decay pipe and Flux Ratio

I generated diverse flux histograms for decay pipe location of 17.3m, 37.3m, 57.3m, and

77.3m (from the MCZERO, which is the upstream end of the horn 1) using FTFP_BERT physics

list: muon neutrino , muon antineutrino ( , electron neutrino (Ve), and electron

antineutrino ( . These plots showed the flux generated throughout the energy level (0.0-20.0

GeV). I used Sumw2() command in ROOT to create error bars on the histograms. Then, I

generated ’37.3m flux / 17.3m flux’, ‘57.3m flux / 17.3m flux’, and ‘77.3m flux / 17.3m flux’

ratio plots by dividing them. I used Sumw2() command in ROOT to create error bars on the

histograms and IntegralAndError() command to calculate the integrated flux ratio for 4 intervals

(0.0-0.5Gev, 0.5-1.5Gev, 1.5-5.0Gev, 5.0-10.0Gev).

4. Analysis

4.1 Flux analysis and Flux Ratio analysis (Helium VS Air)

For more accurate analysis, I overlaid helium and air histograms for neutrino/antineutrino

flux. Therefore, I was able to clearly discern in which decay pipe filling material higher flux was

generated in each region of energy (0.0-20.0 GeV). Moreover, by taking ratio of helium flux

plots over air flux plots, I was able to see which medium generated higher flux. If the ration is

significantly greater than 1, then we can conclude that more flux was generated in helium than

air and vice versa.

4.2 Current event rates analysis and Current event rates Ratio analysis (Helium VS Air)

For more accurate analysis, I overlaid helium and air histograms for neutrino/antineutrino

current event rates. Therefore, I was able to clearly discern in which decay pipe filling materials

higher current event rate was generated in each region of energy (0.0-20.0 GeV). Moreover, by

taking ratio of helium current event rate (both charged and neutral) plots over air current event

rate plots, I was able to see which medium had higher current event rates. If the ratio is

significantly greater than 1, then we can conclude that more current event rates were observed in

helium than air and vice versa.

4.3 Flux analysis and Flux Ratio analysis (Before changes in parameters VS After

changes in parameters)

For more accurate analysis, I overlaid histograms for neutrino/antineutrino flux before and

after changes. Therefore, I was able to clearly discern in whether higher flux was generated

before or after changes. Moreover, by taking ratio of ‘primitive flux plots over modified flux

plots’, I was able to see the effects of changes in parameters. If the ratio is significantly greater

than 1, then we can conclude that changes in parameter reduced the flux.

4.4 Current event rates analysis and Current event rates Ratio analysis (Before changes

in parameters VS After changes in parameters)

For more accurate analysis, I overlaid histograms for neutrino/antineutrino current event rates

(both charged current and neutral) before and after changes. Therefore, I was able to clearly

discern whether higher current event rates were generated before or after. Moreover, by taking

UTA-HEP/IF-005

5

ratio of ‘primitive cceventrate plots over modified cceventrate plots’ and ‘primitive nceventrate

plots over modified nceventrate plots’, I was able to see the effects of changes in parameters. If

the ratio is significantly greater than 1, then we can conclude that changes in parameter reduced

the current event rates.

4.5 Flux analysis and Flux Ratio analysis (decay pipe location of 17.3m control, 37.3m,

57.3m, 77.3m)

For more accurate analysis, I overlaid histograms for neutrino/antineutrino fluxes for each

location of decay pipe. Therefore, I was able to clearly discern whether higher fluxes were

generated as the distance from the MCZERO (upstream end of the horn 1) to the decay pipe

increased. Moreover, by taking ratio of ‘Varied location plots / Default location plots’, I was able

to see the effects of changes in decay pipe location. If the ratio increased as the distance

increases, then we can conclude that increase in distance increases the flux.

5. Results and interpretations

Fig. 2 , flux plots. QGSP_BERT

Fig. 3 , flux plots. FTFP_BERT

UTA-HEP/IF-005

6

5.1 Flux Comparison. Helium VS Air

There were higher flux and flux when the decay pipe filling material was helium.

According to the histogram, throughout the energy realm (0.0-20.0 GeV), neutrino flux in helium

was generally higher than neutrino flux in air. For example, on the flux plot in Fig. 2, peak

for both helium and air was found when the energy was approximately 2.0 GeV; it was observed

to be neutrino/GeV/m2/POT and neutrino/GeV/m

2/POT, respectively

(12.5% higher). Other neutrino flux plots in Fig. 2 and Fig. 3 supported analogous trends. On the

contrary, there were higher flux and flux when the decay pipe filling material was air.

Throughout the energy realm (0.0-20.0 GeV), antineutrino flux in air was generally higher than

antineutrino flux in helium. On the flux plot in Fig. 2, peak for both helium and air was found

when the energy was approximately 2.0 GeV; it was measured to be

neutrino/GeV/m2/POT and 2.6 neutrino/GeV/m

2/POT, respectively. Likewise, other

plots in Fig. 2 and Fig. 3 testified to the trend that higher antineutrino flux is generated in air.

Fig. 4 , flux ratio plots (Helium / Air). QGSP_BERT

Fig. 5 , flux ratio plots (Helium / Air). FTFP_BERT

UTA-HEP/IF-005

7

Energy cut

range 0~0.5GeV 0.5~1.5GeV 1.5~5GeV 5~10GeV

0.9331±0.0010 1.0430±0.0010 1.1080±0.0007 1.0442±0.0021

0.8578±0.0013 0.8343±0.0019 0.9559±0.0018 1.0195±0.0034

0.9960±0.0161 1.0429±0.0132 1.0256±0.0095 1.0292±0.0090

0.9102±0.0170 0.9134±0.0230 0.9362±0.0098 0.9716±0.0093 Table 1. Integrated flux ratio of He to Air. QGSP_BERT

5.2 Flux Ratio Comparison. Helium VS Air

Overall, through the energy realm (0.0~20.0 GeV), ratio was bigger than 1 in neutrino flux

ratio plots in Fig. 4 and Fig. 5; it is apparent that higher proportion of plots was observed above 1.

Since the

, the observation supports the trend that higher neutrino fluxes are

generated in helium. On the other hand, ratio was less than 1 in antineutrino flux ratio plots in

Fig. 4 and Fig. 5; it is apparent that higher proportion of plots was observed below 1. Table 1

supports the trend in the graph. Therefore, it can be noted that air tends to induce higher

antineutrino flux. Both physics lists yielded similar results.

Fig. 6 , charged current event rates plots. QGSP_BERT

Fig. 7 , charged current event rates plots. FTFP_BERT

UTA-HEP/IF-005

8

5.3 Charged current event rates Comparison. Helium VS Air

Overall, there were higher charged current event rates when the decay pipe filling

material was helium; charged current event rates did not vary significantly from helium to air.

For instance, on the charge current event rates plot in Fig. 6, peak for both helium and air was

observed when the energy was approximately 3.0 GeV; it was measured to be CC

Events/GeV/kTon/POT and 42.0 CC Events/GeV/kTon/POT, respectively (14% higher).

plots in Fig. 6 and Fig. 7 demonstrate that charged current event rates are similar in both

medium. Likewise, antineutrino charged current event rate plots for helium and air in Fig. 6 and

Fig. 7 nearly overlapped.

Fig. 8 , charged current event rates ratio plots (Helium / Air). QGSP_BERT

Fig. 9 , charged current event rates ratio plots (Helium / Air). FTFP_BERT

UTA-HEP/IF-005

9

5.4 Charged current event rates Ratio Comparison. Helium VS Air

Overall, throughout the energy realm (0.0~20.0 GeV), ratio was bigger than 1 in muon

neutrino charged current event rates ratio plots in Fig. 8 and Fig. 9. Since the ratio

was

, the observation supports the trend that higher charged

current event rates are yielded in helium; it is apparent that higher proportion of plots was

observed above 1. For and antineutrino charged current event rates ratio histograms, ratio

differed negligibly from 1. Both physics lists produced similar results.

Fig. 10 , neutral current event rates plots. QGSP_BERT

Fig. 11 , neutral current event rates plots. FTFP_BERT

UTA-HEP/IF-005

10

5.5 Neutral current event rate Comparison. Helium VS Air

Overall, there were higher charged neutral current event rates when the decay pipe filling

material was helium; neutral current event rates did not vary significantly from helium to air.

For instance, on the neutral current event rates plot in Fig. 10, peak for both helium and air

was observed when the energy was approximately 3.0 GeV; it was measured to be

NC Events/GeV/kTon/POT and 14.5 NC Events/GeV/kTon/POT, respectively (13.8%

higher). plots in Fig. 10 and Fig. 11 demonstrate that neutral current event rates are similar in

both medium. Likewise, helium and air antineutrino neutral current event rates plots in Fig. 10

and Fig. 11 nearly overlapped.

Fig. 12 , neutral current event rates ratio plots. QGSP_BERT

Fig. 13 , neutral current event rates ratio plots. FTFP_BERT

UTA-HEP/IF-005

11

5.6 Neutral current event rate Ratio Comparison. Helium VS Air

Overall, throughout the energy realm (0.0~20.0 GeV), ratio was bigger than 1 in muon

neutrino neutral current event rates ratio plots in Fig. 12 and Fig. 13. Since the ratio was

, the observation supports the trend that higher charged current

event rates are yielded in helium; it is apparent that higher proportion of plots was observed

above 1. For and antineutrino neutral current event rates ratio histograms, ratio differed

negligibly from 1. Both physics lists produced similar results.

Fig. 14 , flux plots. Helium FTFP_BERT

5.7 Flux Comparison Before changes in parameters VS After changes in parameters

There were higher neutrino and antineutrino flux (both muon and electron) when changes in

parameters were made. According to the histogram, throughout the energy realm (0.0-20.0 GeV),

flux in modified mode was generally higher than flux in primitive mode. For example, on the

flux plot in Fig. 14, peak for modified mode and primitive mode was found when the energy was

approximately 2.0 GeV; it was observed to be neutrino/GeV/m2/POT and

neutrino/GeV/m2/POT, respectively (4.6% higher). Other flux plots in Fig. 14 supported

analogous trends. The probable reason for this trend is that decrease in beam width and increase

in target width and baffle radius may have increased the number of interactions with protons;

hence higher fluxes were produced.

UTA-HEP/IF-005

12

Fig. 15 , flux ratio plots. Helium FTFP_BERT

Energy cut


0.9526±0.0011 0.9550±0.0009 0.9743±0.0006 1.0105±0.0021

0.9661±0.0171 0.9656±0.0113 0.9637±0.0082 0.9826±0.0081

0.9786±0.0015 0.9819±0.0026 0.9980±0.0022 0.9866±0.0040

0.9627±0.0164 0.9812±0.0153 0.9729±0.0087 0.9836±0.0090 Table 2. Integrated flux ratio of primitive mode to modified mode. Helium FTFP_BERT

5.8 Flux Ratio Comparison. Before changes in parameters VS After changes in

parameters

Overall, throughout the energy realm (0.0~20.0 GeV), ratio was less than 1 in all ratio plots

in Fig. 15. Since the ratio was

, the observation supports the trend that higher fluxes

are yielded in modified mode; it is apparent that higher proportion of plots was observed under 1.

Table 2 supports the trend in the graph. Rest of the histograms demonstrated similar trends.

Fig. 15 , charged current event rates plots. Helium FTFP_BERT

UTA-HEP/IF-005

13

5.9 Charged current event rates Comparison. Before changes in parameters VS After

changes in parameters

There were higher neutrino and antineutrino charged current event rates (both muon and

electron) when changes in parameters were made. According to the histogram, throughout the

energy realm (0.0-20.0 GeV), charged current event rates in modified mode was generally higher

than those in primitive mode. For example, on the charged current event rates plot in Fig. 15,

peak modified mode and primitive mode was found when the energy was approximately 3.0

GeV; it was observed to be neutrino/GeV/m2/POT and

neutrino/GeV/m2/POT, respectively (2.4% higher). Other plots in Fig. 15 supported analogous

trends. The probable reason for this trend is that decrease in beam width and increase in target

width and baffle radius may have increased the number of interactions with protons; hence

higher current event rates were produced.

Fig. 16 , charged current event rates ratio plots. Helium FTFP_BERT

5.10 Charged current event rates Ratio Comparison. Before changes in parameters VS

After changes in parameters



, the observation supports the

trend that higher current event rates are yielded in modified mode; it is apparent that higher

proportion of plots was observed under 1. Rest of the histograms demonstrated similar trends.

UTA-HEP/IF-005

14

Fig. 17 , neutral current event rates plots. Helium FTFP_BERT

5.11 Neutral current event rates Comparison. Before changes in parameters VS After


There were higher neutrino and antineutrino neutral current event rates (both muon and

electron) when changes in parameters were made. According to the histogram, throughout the

energy realm (0.0-20.0 GeV), neutral current event rates in modified mode was generally higher

than those in primitive mode. For example, on the charged current event rates plot in Fig. 17,

peak modified mode and primitive mode was found when the energy was approximately 3.0

GeV; it was observed to be neutrino/GeV/m2/POT and

neutrino/GeV/m2/POT, respectively (2% higher). Other plots in Fig. 17 supported analogous

trends. The probable reason for this trend is that decrease in beam width and increase in target

width and baffle radius may have increased the number of interactions with protons; hence

higher neutral current event rates were produced.

Fig. 18 , neutral current event rates ratio plots. Helium FTFP_BERT

UTA-HEP/IF-005

15

5.12 Neutral event rates Ratio Comparison. Before changes in parameters VS After




, the observation supports the trend

that higher current event rates are yielded in modified mode; it is apparent that higher proportion

of plots was observed under 1. Rest of the histograms demonstrated similar trends.

Fig. 19 , flux plots. Helium FTFP_BERT

5. 13 Flux Comparison (17.3m, 37.3m, 57.3m, 77.3m)

There were higher neutrino and antineutrino flux (both muon and electron) when distance of

the decay pipe from the MCZERO (upstream end of the horn 1) increased. For example, on the

flux plot in Fig. 10, peak for each histogram was found when the energy was approximately

2.0 GeV; it was observed to be neutrino/GeV/m2/POT,

neutrino/GeV/m2/POT, neutrino/GeV/m

2/POT, and

neutrino/GeV/m2/POT respectively (on average of 4% increase per every 20m increase in

distance). Other flux plots in Fig. 19 supported analogous trends. The most probable reason for

this trend is that farther away the decay pipe, protons have longer time to decay into neutrinos;

hence, higher fluxes were generated. However, varied locations of the decay pipe overlap with

the dump (place where proton beams that do not interact with the target get transported here),

which would theoretically decrease the length of the decay pipe itself; this may have affected the

results.

UTA-HEP/IF-005

16

Fig. 20 , flux ratio plots. Helium FTFP_BERT

Energy cut


1.1315±0.0013 1.0580±0.0010 1.0945±0.0007 1.1623±0.0024

1.1757±0.0017 1.1961±0.0031 1.1588±0.0025 1.2219±0.0048

1.1775±0.0207 1.2565±0.0148 1.2440±0.0110 1.1192±0.0097

1.2171±0.0239 1.1675±0.0184 1.1369±0.0101 1.0869±0.0100 Table 3. Integrated flux ratio of decay pipe location at 77.3m to 17.3m. Helium FTFP_BERT

Energy cut


1.1059±0.0013 1.0506±0.0010 1.0727±0.0007 1.1040±0.0023

1.1375±0.0017 1.1302±0.0029 1.1118±0.0024 1.1476±0.0045

1.1126±0.0188 1.1752±0.0138 1.1664±0.0099 1.0732±0.0090


UTA-HEP/IF-005

17

Energy cut


1.0805±0.0013 1.0457±0.0010 1.0504±0.0007 1.0478±0.0022

1.0855±0.0016 1.0732±0.0028 1.0618±0.0023 1.0766±0.0043

1.1137±0.0190 1.1111±0.0132 1.0977±0.0093 1.0427±0.0087


5. 14 Flux Ratio Comparison. (17.3m control, 37.3m, 57.3m, 77.3m)

Overall, throughout the energy realm (0.0~20.0 GeV), ratio was greater than 1 in all ratio

plots in Fig. 20 and the ratio decreased as the distance of decay pipe from the target increased.

Since the ratio was

, the observation supports the trend that higher fluxes are

yielded when the decay pipe is farther away; it is apparent that black ratio plot is above both the

blue and red ratio plot. Table 3, 4, 5 support the trend in the graph; integrated ratio of flux ratio

decreases as the distance increases.

6. Conclusions and future work

Helium should be used for decay pipe filling material for the LBNE beam line rather than air.

Higher neutrino fluxes were observed in helium; on the other hand, higher antineutrino fluxes

were found in air. Histograms clearly show that in helium higher muon neutrino flux was

produced throughout the energy realm (12.5% higher); ratio plots further support the trend since

the majority of the plots was observed above 1. Furthermore, when the distance of the decay pipe

from the MCZERO (upstream end of the horn 1) increased, higher muon fluxes were measured;

flux increased on average of 4% per every 20m increase in distance. Moreover, when changes in

beam width, baffle radius, and target width were made, muon fluxes increased by 4.6%.

7. Bibliography

1. http://lbne.fnal.gov/why-neutrinos.shtml 2. Perkins, D.H. 2000. Introduction to High Energy Physics. Cambridge University Press.

The Edinburgh Building, Cambridge., pgs.7-12

3. http://lbne.fnal.gov/collaboration/collab_main.shtml 4. http://lbne.fnal.gov/strategic-plan.shtml 5. http://lbne.fnal.gov/neutrino-beam.shtml

uta-hep/if-005 lbne beam simulation studies · pdf filelbne beam simulation studies...

Documents