LENS: mLENS Simulations, Analysis, and Results

B. Charles RascoLouisiana State University

on behalf of the LENS Collaboration

Why Low-Energy Neutrino Spectroscopy (LENS)?

Compare the photon luminosity of the sun to the luminosity of pp and CNO n energy output from the sun.

Measure the CNO n in order to get a direct measure of the metalicity of the sun.

To get ne energy information from the sun!

Why LENS?

497 keV

115 keV

What signal are we looking for?

Ee = En-QEn

(See R. Bruce Vogelaar’s Presentation J9-5)

ne + 115In ® 115Sn* + b-

Use 115In because reaction has a low Q value (~115 keV)In-loaded (~8% - 10 tons of Indium) liquid scintillator (LAB)

In order to identify the electrons and gammas above background good position and time resolution are required.

One way to accomplish position resolution is with a 3D segmented detectorsuch as a scintillation lattice detector. LENS is a 60x60x60 scintillation lattice detector.

Phys. Rev. Lett. 37, 259 (1976).

What is a Scintillation Lattice?

Thin Container Filled with Liquid ScintillatorContainer Index of Refraction = n1 (Could be air)

Liquid Scintillator Index of Refraction = n2 > n1

What is a Scintillation Lattice?

(Though this animation just shows a Scintillation Plane)

We call this a Scintillation Lattice

What Is LENS?

(See Z. Yokley’s Presentation - J9-6)

mLENS - 6x6x6 – 3” Cubes – Now miniLENS - 9x9x9 – 3” Cubes – Under Construction

LENS – mLENS and miniLENS will show the way...

4 m Water Tank

mLENS and miniLENS

(See D. Rountree’s Presentation J9-7)

What Was Measured?

~.5 mCi 137Cs Source Located Near Center Bottom of mLENS

for ~ 1 hour

Background Runfor ~ 1/2 hour

Longer Background Runfor ~ 1 week

~.5 mCi 137Cs Source

All Runs Triggered on Center Four Top PMT

Trigger PMT

Y=2 Plane

Y=3 Plane

Y=4 Plane

Y=5 Plane

PMT All Approximately Normalized byPrevious Measurements

Background Subtracted 137Cs Data

Raw 137Cs Source (662 keV g)

Background Subtracted 137Cs Source

Background

Normalized Over This Region

40K (1460 keV g)(Compton Edge or Full E Deposit?)

Thorium (2.6 MeV g)(Compton Edge or Full E Deposit?)

Low E Bump

137Cs (Compton Edge or Full E Deposit?)

Simulation of 137Cs Source at Bottom of mLENS

Relative height of low energy bump to high energy bump depends on the trigger level.

Low Trigger Threshold Medium Trigger Threshold High Trigger Threshold

Simulation of 137Cs Source at Bottom of mLENS

Low Trigger Threshold

Low Energy Peak is a Low EnergyDeposit in the Plane. Most LikelySeveral Mostly Forward Compton

Interactions (The Most Probable to Happen) in a Single Cell as the g

Crosses the Plane.

High Energy Peak is a Mixture of theFull Energy Deposit, Full Energy Minus Loss in the Outer Acrylic Shell, and the Compton Edge

Deposit in the Plane.

High Trigger Comparison of Simulation and First 137Cs Measurements

Background Subtracted 137Cs

Simulated 137Cs

Measured data is proportionally normalized, not linearly normalized.

Simulated Number of PE / Proportionally Scaled Channel Number

VT -- R. Bruce Vogelaar, Mark Pitt, Camillo Mariani, S. Derek Rountree, Laszlo Papp, Tristan Wright, Joey Heimburger, Lillie Robinson, Zach Yokley

LSU -- Jeff Blackmon, B. Charles Rasco, Liudmyla Afanasieva, Kevin Macon, Matt Amrit

BNL -- Minfang Yeh BNL

NCCU -- Diane Markoff

UNC -- Art Champagne

The LENS Collaboration

BACKUP SLIDES

Prediction for 3 Plane mLENS with Low Trigger

Measurement with Low Trigger Threshold

And What it Translates to Measuring

Sum Y=2+3+4 PlanesSum Y=2 PlaneSum Y=3 PlaneSum Y=4 Plane

Prediction for 3 Plane mLENS with High Trigger

Measurement with High Trigger Threshold

And What it Translates to Measuring

Sum Y=2+3+4 PlanesSum Y=2 PlaneSum Y=3 PlaneSum Y=4 Plane