MUON FLUX MEASUREMENTS AT THE LSC JRA1-N2 Meeting, Zaragoza, Nov 23 rd 2007 Héctor Gómez Maluenda, University of Zaragoza. [email protected]

MUON FLUX MEASUREMENTS

AT THE LSC

JRA1-N2 Meeting, Zaragoza, Nov 23rd 2007

Héctor Gómez Maluenda, University of Zaragoza.

[email protected]


Outline

Introduction

Detection system features

Preliminary tests at sea level

Measurements in LSC

Outlook

Summary and Conclusions


Introduction

LSC Depth: 2450 mwe

Expected Muon Flux: ~3 10-3 m-2 s-1

• Need to check the theoretical value for the muon flux



• Detectors

2 Plastic scintillators BICRON BC 408 of 80 x 40 x 5 cm3.

2 light guides with PMTs coupled to the scintillators.



• Electronic Chain

NIM Fast – Slow standard coincidence system.



• Readout

C-code based acquisition program using a 32 channel I/O digital card.

Storage of the energy of both detectors and time (up to 100 s accuracy) for each coincidence event allowing energy and time analysis.



Muons produce a coincidence event releasing an energy average of 2 MeV per cm.

<E>T~10 MeV

Most of the gammas coming from natural background (up to ~3 MeV) release all the energy in one detector Rejected event.

Our set up allows to detect muons coming from a solid angle of ~2



• We made some measurements in Zaragoza (200 m above sea level) in order to adjust the DAQ (gain, thresholds…) and to check the efficiency of the system.

• The total muon flux expected for a 2 solid angle is 125 m-2s-1.PDG. S. Eidelman et al., Physics Letters B 592, 1 (2004)



• 3 different regions in the spectra

- Background region.

- Intermediate region.




- Background region.

- Intermediate region.

- Muon region.




Muon Flux

= 105.64 ± 0.02 (stat.) m-2 s-1

Systematic errors (~10%):

- Not 2 solid angle.

- Unconsidered shielding.

- Efficiency less than 100%.

- Lose of muons:

No coincidence.

Less energy deposit than expected.

COMPATIBLE RESULTS


Measurements in LSC

• Location


Measurements in LSC

• Results: 50.8 days of measurement.

= 3.94 ± 0.02 (stat.) ± 0.4 (sys.) 10-3 m-2 s-1

Slightly higher than expected value

WHY?


Measurements in LSC

• A Possible Explanation: Mountain Profile.


Measurements in LSC

• A Possible Explanation: Mountain Profile.

Hall B 5.04 ± 0.06(stat) ± 0.5(sys) 10-3 m-1s-1 +28%

Hall A 3.94 ± 0.02(stat) ± 0.4(sys) 10-3 m-1s-1

Old Lab 3.59 ± 0.04(stat) ± 0.4(sys) 10-3 m-1s-1 -9%


Outlook

Complete measurements in the Old Lab and Hall B at LSC trying to corroborate and quantify the influence of the mountain profile in the muon flux.

Make a Monte Carlo study to estimate the muon flux in the different locations (ongoing).


Summary and Conclusions

We developed and tested successfully an experimental set up to measure the muon flux.

The muon flux measured at the Hall A of the LSC seems to be slightly higher than the expected value regarding the depth of the Lab.

A possible explanation for this difference could be the dependence between the muon flux and the mountain profile.

Preliminary measurements in other locations of the LSC and the Old Lab seem to corroborate this theory.

More accurate measurements and Monte Carlo simulations are ongoing to obtain final conclusions.

MUON FLUX MEASUREMENTS

IN THE LSC


Héctor Gómez Maluenda, University of Zaragoza.

[email protected]


Stability of the Rate

Different orientation


Different Analysis Methods

Method i)

Chu & Chl > 600

Method ii)

Chu & Chl > 170

Method iii)

Chu || Chl >170


Different Analysis Methods

Documents

MUON FLUX MEASUREMENTS AT THE LSC JRA1-N2 Meeting, Zaragoza, Nov 23 rd 2007 Héctor Gómez Maluenda, University of Zaragoza. [email protected]