Physics Case for 5 GeV Neutrino

Factory

Patrick Huber

Center for Neutrino Physics at Virginia Tech

MAP 2014 Winter Meeting

December 3-7, 2014, SLAC

P. Huber – p. 1

Baseline neutrino factory

464 m

Muon Decay

Ring

Linac optionRing option

Proton Driver: Neutrino

Beam

Ta

rge

t

Bu

nc

he

r

Ph

as

e R

ota

tio

n

Co

olin

g

2.8–10 GeV RLA

0.8–2.8 GeV RLALinac to 0.8 GeV

To Accel.

To Decay Ring

From

Acceleration

From Cooling

IDS-NF/2012 4.0 10 GeV muon energy

1E21 useful muon decays per

straight and polarity, in 1E7 s

2 000 km baseline

100 kt magnetized iron detector

(MIND)

Based on a 4 MW proton driver,

which would have become available

as part of Project X phase IV, i.e. in

the 2030s

Difficult to identify synergies with LBNF.

P. Huber – p. 2

NF performance

CK

M2011

CK

M2011

LBNE + Project X H2.3MW, 34ktL

T2HK H0.7MW, 560ktL

Daedalus H MWL + T2HKΝ1+2+2.5+2.5

T2HK + NuSTORM

IDS-NF

LBNO H0.8MW, 100ktL

ESS H5MW, 500ktL

GL

oB

ES

20

13

D∆ at 1ΣΘ23=40é

0 5 10 15 20 25 300.0

0.2

0.4

0.6

0.8

1.0

D∆@°D

Fra

ction

of∆

IDS-NF (4MW, 100kt), corresponding to 1021 useful muon decays p.a.

P. Huber – p. 3

An entry level neutrino factory?

In order to maximize synergies with the existingprogram, MASS identified the following questions

• Can a neutrino factory work at 1 300 km baseline?

• Are there better detector choices?

• What is the minimum number of muon decaysneeded?

The answers to those questions are interrelated, manyoptions have been studied, one possible scheme hasbeen introduced in Christensen, Coloma, PH, PRL111 061803 (2013).

P. Huber – p. 4

NuMAXNuMAX – NeUtrinos from Muon AcceleratorscompleX

• 1 300 km baseline implies a beam energy of5 GeV

• 5 GeV beam energy makes liquid argon a veryattractive detector choice

• Magnetized liquid argon allows the detection ofν̄e and νe

As a result proton driver beam power of 1 MW and adetector mass of 10 kt yield already good physicssensitivities.

P. Huber – p. 5

Detector choicesA detector suitable for a 5 GeV NuMAX beam shouldhave

• good efficiency down to 2 GeV neutrino energy

• a magnetic field – for muon charge ID

• fine granularity – for electron neutrinointeractions

Possible detector systems

• Totally Active Scintillator Detector (TASD) withmagnetic field – simulation studies exist

• Liquid argon TPC (LAr) with magnetic field –needs a simulation study

Also, Magnetized Iron Detector (MIND) with a largermass may be used. P. Huber – p. 6

Detector assumptions

TASD

Channel Effs. τ Rej. NC/CID/FID Rej. ∆E/E

νµ app. 73%-94% 0% 99.9% 0.2/√E

νe app. 37%-47% 0% 99% 0.15/√E

νµ dis. 73%-94% 0% 99.9% 0.2/√E

Magnetized LAr

Channel Effs. τ Rej. NC/CID/FID Rej. ∆E

νµ app. 80% 0% 99.9% 0.2/√E

νe app. 80% 0% 99.9% 0.15/√E

νµ dis. 80% 0% 99.9% 0.2/√E

ντ backgrounds included

P. Huber – p. 7

The Platinum channel

Θ23=40°

gol+dis

gol+plat+dis

LBNE-CDR

EΜ=5GeV; 2�1020Μ decays�yr

M=10 kt; L=1300kmGLoBES 2013

è

7 8 9 10 11

-100

-50

0

50

Θ13@°D

∆@°D

The νµ → νe channel isthe CPT conjugate of theν̄e → ν̄µ channel

As a result matter effectseffectively cancel

This has been known forquite a while, but the effectis only relevant for largeθ13

P. Huber – p. 8

CP precision

Θ23=40°

gol+dis

gol+plat+dis

non-magnet

LBNE-CDR

D∆ at 1Σ

EΜ=5GeV; 2�1020Μ decays�yr

M=10 kt; L=1300km

GLoBES 2013

-150 -100 -50 0 50 100 1500

10

20

30

40

50

60

∆@°D

D∆@°D

Solid line – magnetizedLArDashed line – magnetizedTASD

The obtainable precisionis everywhere better thanLBNE10 by about 9 de-grees (1/3)

P. Huber – p. 9

CP violation

Θ23=40°

gol+dis

gol+plat+dis

non-magnet

LBNE-CDR

CPV

EΜ=5GeV; 2�1020Μ decays�yr

M=10 kt; L=1300km

GLoBES 2013

-150 -100 -50 0 50 100 1500

1

2

3

4

5

6

7

∆@°D

SignificanceHΣL

Significant advantage forCP violation

P. Huber – p. 10

Mass hierarchy

Θ23=40°

gol+dis

gol+plat+dis

LBNEmini

MH

EΜ=5GeV; 1020Μ decays�yr

M=10 kt; L=1300km

GLoBES 2012

0.0 0.2 0.4 0.6 0.8 1.00

5

10

15

Fraction of ∆

SignificanceHΣL

Same for mass hierarchy,clear advantage

P. Huber – p. 11

RemarksNF detectors probably have to be undergroundbecause of large duty factor.

4-6 GeV muon energy works also, shallow optimumaround 5 GeV.

A full NF would be a 5 GeV machine, maybe with alarger LAr detector – performance en par withIDS-NF baseline – no energy or baseline staging.

Muon based neutrino beams, NuSTORM andNuMAX, can deliver virtually systematics-freemeasurements for both short and long-baselinephysics – path to unique levels of precision.

P. Huber – p. 12

NuMAX performance

P. Huber – p. 13

Next steps. . .

• Need to verify magnetized LAr performance –since there is no reconstruction software we mayresort to a hand scanning study. MicroBooNEexperience indicates that we need about 10-20man-weeks.

• Monte Carlo production, according to LarSoftcollaboration, not a big problem, needs about 1man-week of additional software development

P. Huber – p. 14

Summary

• Full NF – best performance of all technologies

• NuMAX addresses many of the issues of the fullNF in terms of timeliness and synergy withLBNE

• NuMAX starts at 1% of full NF exposure →incredible upgrade potential, basicallysystematics free

• The evolution from NuSTORM over NuMAX toNuMAX+ provides unparalleled capabilities forhigh precision measurements at both short andlong baselines, due to virtual absence of beamsystematics.

P. Huber – p. 15