Precise measurement of - PowerPoint Presentation

Slide1

Precise measurement of solar oscilation parameters using the stereo-calorimetric system of JUNO

Frédéric Perrot on behalf of the JUNO SPMT group IN2P3 – CENBG - Université de Bordeaux

1

GDR Neutrino, Paris, LPNHE,

Novembre 21, 2017

Slide2

2

Schematic

view of the JUNO detector

Top

TrackerWater Pool (D=43 m)Central Detector

20,000 tons of LS in an acrylic sphere (D=35.4 m)

Steel

Truss

holding

PMTs

17500 x 20’’

PMTs

(LPMT)25000 x 3’’PMTs (SPMT)

Why

using

two systems of PMTs ?

Slide3

Large and Small PMT systems

3We can look at the same events with two independent and complementary

instruments!

LPMT system: 17,000x20’’

PMTs

NNVT MCP-PMT

(12,000

units

)

Hamamatsu R12860

PMT (5,000

units

)

Photon

coverage

: 75%

Nb of

photoelectron @1 MeV ~ 1200

Main

calorimetric

system

HZC-

Photonics

XP72B22 PMT

S

PMT system: 25,000x3’’

PMTs

Photon

coverage

: 2%

Nb of

photoelectron

@1 MeV ~ 35

Aid

to

calorimetry

(

stereo

)

+

standalone

physics

Slide4

Motivation for stereo calorimetry in JUNO

4Energy resolution of current LS-based neutrino experiments

Experiment

Detector Target

Mass (tons)Energy resolutionKamLAND

10006% /√E

Double Chooz

30

8% /√E

Daya

Bay

16

RENO

20

Borexino

300

5% /√E

JUNO20 0003% /√E

→

Energy

resolution

is

dominated

by the

number

of

photoelectrons

detected

Next

generation

detector (JUNO):

energy

resolution

will

be improved by more than

a factor 2

N

o more

dominated

by

photostatistics

(

stochastic

term σST) but by systematic uncertainties (non-stochastic term σNST)

Example

: Double Chooz

Slide5

Motivation for stereo calorimetry in JUNO

5Goal : to reach a 3% energy

resolution @ 1 MeV Stochastic

term: depends

on photostatistics (~1200 PE)Non-stochastic

term: residual

issues

after

calibration

Challenge for JUNO :

t

o control the non-

stochastic

term

at an

unprecedented level

never achieved (< 1%)

 

Typical

LS

experiments

:

σ

NST

~ 2%

JUNO

Slide6

Two calorimetry observables in LS exp.

6Energy depositionLiquid Scintillator

MeV→PhotonsPhotoMultiplier TubePhotons

→PhotoElectrons (PE)

Mean PMT illumination λ

= < N(PE) > / PMT

PMT

Charge

Integration

Photon

Counting

λ

> 0.5

PE =

charge

gain

λ

< 0.5

PE = hit

PMT

Different

systematics

Single

photoelectron

threshold

PMT gain

linearity

Gain = f(PE) ?

REDUNDANCY

Slide7

7

Two

calorimetry observables in JUNO

Only

charge

integration

Both

observables

JUNO

LPMT system

has the

highest

dynamic

range

:

from 0.07 PE/PMT (center) to 10 PE/PMT (edge) @1 MeV  charge extraction not trivial with gain depending

on number

of PE

JUNO

SPMT system

is

always

in

Photon

C

ounting

mode

Dynamic

range @ 1 MeV

Slide8

Stereo calorimetry: energy reconstruction

8Several parameters are affecting the energy reconstruction

Uniformity: position dependent Stability

: time dependent

Linearity: energy dependent

E =

PE

 

E[MeV] =

PE

 

For a

wide

dynamic

range,

correlation

among

f

terms

is

no more

negligible

(

degeneracy

)

E[MeV] =

PE

 

For a

limited

dynamic

range,

f

terms

are

evaluated

independently

 

→

Difficult

to

disentangle

all the

effects

with

calibration sources

Slide9

Co-60 calibration (simulation)9

LPMTSPMTTrue

and Reconstructed energy at a given

energy (here

2.6 MeV)Much better agreement

(negligible charge non-linearity

for 3’’PMTs)

1%

deviation

A charge non-

linearity

at a

given

energy

for LPMT

can

be taken

as a spatial non-uniformity →

can

b

e

corrected

by SPMT system

Slide10

Physics

case with the SPMT system

Slide11

SPMT system as an aider to LPMT system11

1. High precision calorimetry (stereo or double calorimetry) → Improve

response systematics within IBD physics

→ Aide

to achieve <3% resolution @ 1 MeV2.

Physics: standalone

measurement

of

solar

oscillation

parameters

→

Ensure accurate

physics results

and validate energy

scale3. Improve inner-detector µ-reconstruction

resolution→ Aide

9

Li/

8

He

tagging

/

vetoing

4. High rate Supernova pile-up (if

very

near

)

→ Minimise

bias

in

absolute

rate &

energy

spectrum

5.

Complementary

readout info : time resolution, dynamic range…

Slide12

12

Solar oscillation parameters with

JUNOJUNO: unique experiment

able to

measure precisely 4 oscillation parameters: θ

13, θ12, Δm

21

2

and |

Δ

m

31

2| from reactor neutrinos with the LPMT system

Oscillation

parameter

Current precisionJUNO precision

|Δm

31

2

|

1.7%

~0.5%

Δ

m

21

2

2.3%

~0.6%

sin

2

(

θ

12

)

5.8 %

~0.7%

sin

2

(

θ13)3.3%~15%

Solar oscillation

parameters

(

Δ

m

21

2

,sin

2

θ

12) measured with a precision below 1%  Crucial constrains for the future unitarity test of the PMNS matrix in the 3-flavor neutrino model

slow

fast

Slide13

Solar oscillation

parameters with JUNO

Solving the tension

between

Kamland results and solar models

for the Δm212 parameter

At

this

level

of

accuracy

(<1%),

it

is

crucial to control the systematic

uncertainties13KamLAND

Is the SPMT system able to perform a

standalone

measurement

in

order

to cross-check the LPMT

results

?

Slide14

14

Solar parameters study with SPMT

Simulated

i

deal

IBD

spectrum

(

true

)

Simulated

spectrum

of collected PE’s

Detector

response matrix

for 25,000 x 3’’ PMTs(correction for the spatial non-uniformity)NPEEtrue

(MeV)Etrue (MeV)

N

PE

35 PE/MeV @ center

(18%

resolution

)

Yury

Malyshkin

Slide15

Δm21

2sin2θ12

Approach

:

Δχ2

method

N

PE

spectra

from

fake

MC

experiments (100k

events) were

calculated over the (sin2θ12,Δm212)-space and

compared with the nominal one (10M events)

Χ

2

was

used

to

estimate

how a

spectrum

with

varied

parameters

defers

from

the nominal one

MCNominalSimultaneous variation of two

or more parameters can

mimic

the nominal

spectrum

Slide16

SPMT

sensitivity studyStatistics : 2000 days

, 100% efficiencyReactor

spectrum

3% rate2% shape uncertainty

Reactor

spectrum

How the uncertainties and backgrounds affect the precision on solar parameters?

Slide17

17SPMT, all uncertainties

1σ2σ3σ

The promising results of this preliminary

study has been cross-

checked with an independant approach using

continuous distributions (Hiroshi Nunokawa)

Impact of

separate

&

combined

uncertainties

on the

solar

parameter sensitivity

SPMT

sensitivity

study

Good agreement between the two independent approaches with SPMT

1σ

2

σ

3

σ

Backgrounds (mainly

g

eo

-

ν and accidentals) play an important

role

Impact of correlated flux uncertainty limited thanks to complementarity of

rate+shape

information

.

Slide18

18

SPMT sensitivity study: first conclusions

Very competitive sensitivities compared to JUNO LPMT system with different systematics (redundancy!)

Sensitivity

of the SPMT system to sin2θ12 and Δm212 is

estimated with the Δχ

2

method

The SPMT system

standalone

is

able to

improve the sensitivity on

these parameters by a factor 3-4

compared to the current best estimationsExpected sensitivities with

SPMT: sin2θ12 ~ 1%

Δ

m

21

2

~ 0.5%

Slide19

SPMT system as an aider to LPMT system19

1. High precision calorimetry (stereo or double calorimetry) → Improve

response systematics within IBD physics

→ Aide

to achieve <3% resolution @ 1 MeV2.

Physics: standalone

measurement

of

solar

oscillation

parameters

→

Ensure accurate

physics results

and validate energy

scale3. Improve inner-detector µ-reconstruction

resolution→ Aide

9

Li/

8

He

tagging

/

vetoing

4. High rate Supernova pile-up (if

very

near

)

→ Minimise

bias

in

absolute

rate &

energy

spectrum

5.

Complementary

readout info : time resolution, dynamic range…

Slide20

20

Status of SPMT Hardware

Slide21

2

≈20m

MAIN

DAQ

SURFACE

Low Voltage

Clock

Data

Under Water Box

128 ch.

Photomultipliers

High Voltage

Decoupling

HV/Signal

Front-End Readout

DAQ

≈100m

SPMT system sketch

25,000

PMTs

~200 UWB

21

Slide22

22

SPMT system schematics

SPMT Hardware : consortium between China, Chile and France

International technical

coordination by IN2P3 in France

Slide23

23

3’’ PMTs

SPMT is a very new system in JUNO !

2014-2015

: starting point of the idea and physics studies

Feb

’

2017

:

a

ccepted

by the JUNO Collaboration

May 2017

: successful

bidding with HZC

company (China)

Jan 2018- Dec 2019: production of 25,000 x 3’’ PMTs !!

HZC-Photonics

XP72B22 PMT

First 5 tubes are

under

investigation

on time

with

the

overall

schedule

for JUNO (2020)

Parameter

Requirement

QE x CE

24%

TTS (

σ

)

<2.1 ns

HV @ 3.10

6

<1300 V

SPE

resolution

35%

Dark

rate @1/3 PE

<1.8 kHz

→

bulb

shape

optimized to improve TTS

Slide24

24

UWB studies

2017-2018: prototyping and tests in France (CENBG, CPPM)

2018-2019

: production of the 200 UWB in Chile

Cables

and

underwater

connectors

:

c

urrent

investigation

with companies

UWB

studies

Water pressure

test tank

Slide25

25

Front-End Board

Main deliver of IN2P3 for SPMT(APC, CENBG, OMEGA,

Subatech)

8

CATiROC

ASICS per

board

:

16 input

channels

Pre

-amplifier for

each

channel

Programmable trigger threshold

Output handled by a FPGAProduced and

delivered by OMEGA

Slide26

26

Front-End BoardBlock

diagram and routing done in spring 2017

4

bare PCB produced in june 2017

Slide27

27

Front-End Board

1st PCB populated in July 2017 !

End of 2017

: 3 boards to be fully tested

and characterized in France (APC, CENBG, Subatech

)

First part of 2018

: new

updated

version of the

boards

+ tests

Fall

2018 

Mid-2019: production of the 200 boards

Slide28

28

3’’ PMTs production and testing

HZC companyPMT prod+mass testing

Dongguang

UniversityAcceptance

+sub-sample deep t

esting

JUNO site

Installation+

commissionning

Slide29

29

SPMT schedule

25 000 PMTs

delivered by the end of 2019

SPMT system delivered by the end of 2019A lot to do but

schedule under control

Slide30

30

Summary and ConclusionsJUNO

will use 2 systems LPMT+SPMT in order to achieve

a high precision

calorimetry for mass hierarchy determination with 3% energy

resolution @1MeV (

systematics

<1%)

Physics

with

SPMT:

standalone

measurement of solar

oscillation parameters very

promising among

other physics (Supernova)SPMT hardware:production and testing

of 25000x3’’ PMTs in 2 years (2018-2019) by HZC

company

Production of 200 Front-End

boards

and UWB

 main

deliver

of

IN2P3

involving

5 IN2P3

laboratories

CDR

paper

on SPMT system

will

be

available

soon

Slide31

31THANK YOU