the grams project · tsuguo aramaki, slac ipmu apec seminar july 22nd 2019 the grams project dual...

T S U G U O A R A M A K I , S L A C

I P M U A P E C S e m i n a r

J u l y 2 2 n d 2 0 1 9

THE GRAMS PROJECT DUAL MEV GAMMA-RAY AND DARK MATTER

OBSERVATORY

outlineDark Matter Search with Antimatter

Current status and recent results of indirect dark matter search Why is antimatter survey important? Antimatter-based dark matter search with GAPS and GRAMS

MeV Gamma-Ray Observations Current status of MeV gamma-ray observations Why are MeV gamma-ray observations important? MeV gamma-ray observations with GRAMS

GRAMS Current Status and Future Prospects R&D Program Application to other fields

Summary GRAMS First Paper: arXiv:1901.03430 Accepted in Astroparticle Physics

Aramaki et al., 2019

https://arxiv.org/abs/1901.03430

Dark Matter Search

Dark Matter in Astrophysical Phenomena

N A S A / E S A

G A L A X Y C L U S T E R S G R AV I TAT I O N A L L E N S I N G

EVIDENCE FOR DARK MATTER

INVISIBLE/MISSING MASS = DARK MATTER

G A L A X Y I N A C L U S T E R

E A R T H

I M A G E O F D I S TA N T O B J E C T PAT H O F L I G H TP AT H O F L I G H T

!4

Z W I C K Y I N 1 9 3 0 S C O M A C L U S T E R

G A L A X I E S M O V I N G T O O FA S T !

I M A G E O F D I S TA N T O B J E C T

D I S TA N T O B J E C T

I N V I S I B L E / M I S S I N G M A S S F O R D I S T O R T E D F I E L D

I N V I S I B L E / M I S S I N G M A S S F O R H I G H V E LO C I T Y

COMPOSITION OF THE UNIVERSE !5

NO DM, NO LIFE.

SNAPSHOT OF THE EARLY UNIVERSE when electrons and protons were recombined

TEMPERATURE FLUCTUATION PR OVIDES COMPOSITION/EVOLUTION OF THE UNIVERSE

Atoms5%

Dark Matter27%

Dark Energy68%

COSMIC MICROWAVE BACKGROUND

27% OF OUR UNIVERSE IS DARK MATTER (DM) Large scale structure and galaxy clusters were created

by dark matter density fluctuation in early universe

DARK MATTER PROFILE

P L A N C K

ASTROPHYSICAL PHENOMENA INDICATE THAT DM SHOULD BE:

!6

VARIOUS DM MODELS ARE PROPOSED TO EXPLAIN ASTROPHYSICAL PHENOMENA

1) LONG LIFETIME Stable particle on galactic time scale Otherwise DM wouldn’t be seen in Astrophysical phenomena

2) VERY SMALL INTERACTION WITH NORMAL MAT TER Or else DM would have been easily detected long time ago

3) NON RELATIVISTIC (SLOW) Otherwise there would be lower density fluctuation in the early universe and less large scale structures in the present

Popular dark matter candidates (m>10 GeV)

WEAKLY INTERACTING MASSIVE PARTICLE = WIMP (> 10 GeV)

RELIC ABUNDANCE (LEFTOVER)

FREEZE-OUT

Larger the cross-section = Less Relic DM Smaller the cross-section = More Relic DM

DM

DM

SM

SMISOLATED THEN DM IS FROZEN OUT

LEFT

OVER

( I I) UNIVERSE EXPANDED AND COOLED DOWN

!7

(I) THERMAL (CHEMICAL) E QUILIBRIUM

DM

DM

SM

SMMIXED IN HOT SOUP

SM = Standard Model Particle DM = Dark Matter Particle

IN EARLY UNIVERSE

DM Relic Abundance

NO SIGNS OF DETECTION IN DM SEARCH → MORE FOCUS ON LOW-MASS DM

WIMP weak-scale interaction cross-section coincidentally gives right dark matter relic abundance seen in astrophysical phenomena

Other Dark Matter candidates!8

SIMPs/ELDERS

UltralightDarkMa5er

Muong-2

Small-ScaleStructure

Microlensing

DarkSectorCandidates,Anomalies,andSearchTechniques

HiddenSectorDarkMa5er

SmallExperiments:CoherentFieldSearches,DirectDetecIon,NuclearandAtomicPhysics,Accelerators

GeV TeVkeVeVneVfeVzeV MeVaeV peV µeV meV PeV 30M�

WIMPsQCDAxion

≈

GeV TeVkeVeVneVfeVzeV MeVaeV peV µeV meV PeV 30M�

≈

Beryllium-8

BlackHoles

HiddenThermalRelics/WIMPlessDM

AsymmetricDM

Freeze-InDM

Pre-InflaIonaryAxion

Post-InflaIonaryAxion

US COSMIC VISIONS 2017 (arXiv:1707.04591)

XENON LUX/LZ

PANDA-X DarkSide

XMASS …

SUPERCDMS CRESST SENSEI

…

GAPS GRAMS

BESS AMS-02

Fermi …

nDM ∝ 1/mDMton-scale detector

kg-scale detector Low-threshold

https://arxiv.org/abs/1707.04591

dark matter searches

P L A N C K

LHC

DIRECT DM SEARCH - DM interaction inside the detector - Measure scintillation, charge, phonon - Underground lab to minimize cosmic-rays

COMPLEMENTARY SEARCHES ARE CRUCIAL TO ILLUMINATE THE NATURE OF DM

!9

M. ATTISHA

LZ/LUX, XENON, DarkSide SuperCDMS

FERMI, VERITAS, AMS-02 GAPS, GRAMS

DM SM

DM SM

COLLIDER SEARCH - Artificially produce DM particles - Measure missing energy/momentum - Mono-X search to trigger events

INDIRECT DM SEARCH - Measure DM annihilation/decay products

INDIRECT Dark Matter SEARCH

aD M

D Mq , h , W ,

e + , γ, ν, p , d , n … _ _ _

POSITRON: AMS-02, PAMELA, DAMPE…

GAMMA RAY: FERMI-LAT, VERITAS, CTA, GRAMS…

NEUTRINO: ICECUBE, ANTARES…

ANTIPROTON: AMS-02, PAMELA, BESS, GAPS, GRAMS

ANTIDEUTERON: AMS-02, BESS, GAPS, GRAMS

ANTIHELIUM: AMS-02, GRAMS

!10

MEASURE DM ANNIHILATION/DECAY PRODUCTS

COMPLEMENTARY SEARCHES WITH DIFFERENT DETECTION METHODS AND BACKGROUND MODELS ARE CRUCIAL TO VALIDATE DM SIGNATURES

Recent Results from fermi-lat

Possible DM signatures from Galactic Center Region (GCE) Inconsistent with dwarf spheroidal galaxy (dSph) observations

(recent observations for new dSphs show some small excess)

FERMI GALACTIC CENTER EXCESS (GCE) ~50GeV DM or astrophysical objects?

Daylan et al., 2016

gamma-ray excess observed

!11

Launched in June 2008, targeting 20MeV - 300GeV gamma-rays

— Fermi Dwarf Galaxy Observation (Ackermann et al., 2015)

10-25

10-27

10 100 1000

10-26

Thermal Relic Cross Section (Steigman et al., 2012)

mᵪ [GeV]

<σv

> [c

m3 /

s]

Excluded

Fermi Galactic Center Excess — Calore et al., 2014 — Daylan et al., 2014 — Abazajian et al., 2015

10-24

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Propagation model: MED

DIFFICULT TO VERIFY DM SIGNATURES DUE TO MIMIC SIGNAL FROM BACKGROUND NEED A NEW APPROACH/EXPERIMENT TO VALIDATE THE RESULTS

E k2 Flu

x (G

eV m

-2 s

-1 s

r-1 )

Ek (GeV)

bkgdm

AMS-02

10-4

10-3

10-2

10-1

100

101

10-1 100 101 102 103

Recent Results from ams-02

P L A N C K

~ 5 0 G e V D M ?

Cui et al . 2016)

NEED A NEW APPROACH, EXPERIMENT TO VALIDATE THE RESULTS

!12

Launched in May 2011, targeting cosmic-rays including antiparticles

Possible DM detection in antiproton measurements Possible detection of antiheliums and antideutrons

▶ Antiproton excess: ~50GeV DM (consistent with Fermi GCE) or cosmic-ray interaction? ▶ Antiheluim detection:

▶ If from DM, a large excess should be seen in the antiproton/antideuteron fluxes? ▶ antimatter clouds in our galaxy?

So far, 6 3He, 2 4He candidate events reported _ _

WHY ANTIDEUTERONS?BACKGROUND-FREE DM SEARCH AT LOW-ENERGY

~ 400x

BKG: Ibarra et al., 2013

PRIMARY FLUX DM ANNIHILATION/DECAY

HADRONIZ ATION PROCESS

_ p

_ n

DARK MATTER ANNIHILATION

q,h,W… DM

DM

COALESCENCE PROCESS (PC)

_ d

SECONDARY FLUX COSMIC RAY INTERACTION

p (CR) +H (ISM)→ p + H + p + n + p + n_ _

_ d

!13

AMS-02 AMS-02

BESS upper limit

GAPS

— DM, mᵪ = 30GeV

Kinetic Energy per Nucleon [GeV/n] 0.1 1 10 100

10-7

10-5

10-3

10-8

10-6

10-4

10-9 Ant

ideu

tero

n Fl

ux [

m-2

s-1 s

r-1 (

GeV

/n)-1

]

GRAMS

— background

GAPS FIRST SCIENCE FLIGHT IS SCHEDULED FROM ANTARCTIC IN 2021 GRAMS: NEXT GENERATION EXPERIMENT


LSP: Donato et al., 2008

Concept proven with accelerator beam test X-ray yields measured with different targets Cascade model developed to predict X-ray yields

Gaps/GRAMS Detection concept

P L A N C K

MEASURE ATOMIC X-RAYS AND ANNIHILATION PRODUCTS

The antiparticle slows down & stops, forming an excited exotic atom

A time of flight (TOF) system tags candidate events and records velocity

De-excitation X-rays provide signature

Annihilation products provide additional background suppression

p

π+

π-

π-

30keV

44keV

67keV

π-

π+

_ d

Refilling e-

X-RAY

X-RAY

X-RAY

Eγ = zZ( )2 M*

me* RH

1nf2−1ni2

⎛

⎝⎜⎜

⎞

⎠⎟⎟

π-

NUCLEAR ANNIHILATIONpπ-

π+

Auger e-

ATOMIC TRANSITIONSn=nK~15

no,lo

n=6

n=7

n=8

n=9

n=1

n=2

π0

π+

Plastic Scintillators, TOF (time-of-flight)

Si(Li) Detector

EXOTIC ATOM

Si

_ d

Aramaki, et al., 2013

!14

Gaps/GRAMS antideuteron identification technique

P L A N C K

CR p, e± REJECTION: ANTIPROTON AND ANTIDEUTERON SELECTION Select slow particles with TOF Simultaneous detection of secondary/annihilation products (pions/protons)

▸ Slow CR p and e± may not be able to produce secondary particles

atomic X-rays from exotic atom ▶ different energy

pion/proton multiplicity ▶ more for antideuterons

stopping range (depth sensing) ▶ antideuterons go deeper

dE/dX energy deposit in layers ▶ more for antideuterons

ANTIDEUTERON IDENTIFICATION FROM ANTIPROTONS

EXPECTED BACKGROUND/MIMIC EVENTS ~0.01

!15

S i ( L i ) D E T E C T O R : 4 inch, 2.5mm thick wafer ▶ 10 layers, about 140 Si(Li) detectors/layer ▶ Segmented into 8 strips

>3D particle tracking ▶ Energy/timing resolution: 4 keV, ~100 ns ▶ Operation temperature: -40C

cooled with oscillating heat pipe (OHP) ▶ Dual channel electronics

20-80 keV: X-rays 0.1-50MeV: charged particles

GAPS Detector

2 m

1 . 6 m

2 m

3 . 6 m

1 . 6 m

3 . 6 m

T O F P L A S T I C S C I N T I L L AT O R S : 18cm x 1.6m x 5mm ▶ Identify incoming charged particles ▶ 1m separation between inner/outer TOF ▶ Timing resolution: 0.5ns, SiPMs on each end

WELL-STUDIED, WIDELY-USED SI(LI) AND PLASTIC SCINTILLATORS SUCCESSFULLY DEMONSTRATED THE PERFORMANCE IN THE ENGINEERING FLIGHT

!16

LArTPCSiPMs

Anode wires/pads (X-Y plane)

E-FI

ELD

Segmentation

Plastic Scintillators : TOF - measure velocity and incoming angle LArTPC : Calorimeter and particle tracker

▶ Scintillation light at SiPMs to trigger events ▶ Wires/pads on anode plane (X, Y), drift time (Z) to provide a 3D image/track ▶ Well-studied, widely-used in large-scale DM/neutrino experiments Scintillation light localized by segmentation to reduce coincident background

!17GRAMS Detector

LARTPC DETECTOR SURROUNDED BY PLASTIC SCINTILLATORS LARTPC MEASURES SCINTILLATION LIGHT AND IONIZATION ELECTRONS

pπ+

π-

π-

π-

π+

_ d Plastic Scintillator

LAr TPCX-ray

X-ray

X-ray

Scintillation Light Ionization Electrons

<σv

> [c

m3 /

s]

10-25

10-27

10 100 1000

10-26

Thermal Relic Cross Section (Steigman et al., 2012)

mᵪ [GeV]

Excluded

10-24

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GAPS

GRAMS

Fermi Galactic Center Exces Daylan et al., 2016 Abazajian et al., 2016 Calore et al., 2015

AMS-02 Antiproton Excess Cui et al., 2016

Fermi Dwarf Galaxy Observation Ackermann et al., 2015

AMS-02

BESS upper limit

GAPS

— DM, mᵪ = 30GeV — background

Kinetic Energy per Nucleon [GeV/n] 0.1 1 10 100

10-7

10-5

10-3

10-8

10-6

10-4

10-9 Ant

ideu

tero

n Fl

ux [

m-2

s-1 s

r-1 (

GeV

/n)-1

]

AMS-02

S/B ~ 400

GRAMS

GRAMS COULD FULLY INVESTIGATE FERMI GCE AND AMS-02 ANTIPROTON EXCESS CURRENTLY EVALUATING GRAMS ANTIHELIUM SENSITIVITY

!18GRAMS Sensitivity in DM Parameter Space

STRONG TENSIONS WITH FERMI GCE/DSPHS AND AMS-02


MeV Gamma-Ray Observation

Current Status of MeV Gamma-Ray Observations!20

MeV-gap

GAMMA-RAYS IN MEV REGION POORLY EXPLORED = “MEV GAP”

Takahashi et al., 2013

ASTROPHYSICAL OBJECTS ▶ Neutron stars: high matter density ▶ Magnetars: strong magnetic field ▶ AGNs/Blazars: powerful jets ▶ Cosmic MeV gamma-ray background

GAMMA-RAY LINE STUDY ▶ Positron annihilation: 511 keV ▶ Nuclear lies are typically in ~MeV ▶ Radioactive isotopes provide physical condition during nucleosynthesis

▶ Core-collapse SNe: 26Al (1809keV), 60Fe (1173keV, 1333keV), 44Ti (1157keV) ▶ Thermonuclear SNe: 56Co (847keV) ▶ Neutron capture: 2H (2223keV) ▶ Cosmic-ray interactions: 12C* (4438keV)

MULTI-MESSENGER ASTRONOMY ▶ EM counterparts of NS-NS mergers ▶ r-process in neutron star mergers/remnants

DARK MATTER SEARCH ▶ MeV gamma rays from DM annihilation

MeV Gamma-Ray Science!21

1001010.1E [MeV]

Gamma-ray lines

Transition of physical processes

MeV-gapInoue et al., 2019

Wu et al., 2019

Why is it difficult to measure MeV Gamma-rays?!22

▶ Compton scattering dominates in the MeV energy region ▶ Both energy & position resolutions need to be good for event reconstruction

▶ Challenging to have a large-scale detector

NIST Data Base

— Total — Photoabsorption — Compton Scattering — Pair Production

E1<latexit sha1_base64="zeWOiLSXOAiRgl4Nz8pGKBEB1T0=">AAAB6nicdZDNSgMxFIXv1L9a/6ou3QSL4KpMitjpriCCy4rWFtqhZNJMG5rJDElGKEMfwY0LRdz6RO58GzNtBRU9EPg4515y7w0SwbVx3Q+nsLK6tr5R3Cxtbe/s7pX3D+50nCrK2jQWseoGRDPBJWsbbgTrJoqRKBCsE0wu8rxzz5Tmsbw104T5ERlJHnJKjLVuLgd4UK64Vdd1McYoB1w/dy00Gl4NewjnkVUFlmoNyu/9YUzTiElDBdG6h93E+BlRhlPBZqV+qllC6ISMWM+iJBHTfjYfdYZOrDNEYazskwbN3e8dGYm0nkaBrYyIGevfWW7+lfVSE3p+xmWSGibp4qMwFcjEKN8bDbli1IipBUIVt7MiOiaKUGOvU7JH+NoU/Q93tSq2fH1WaXrLcxThCI7hFDDUoQlX0II2UBjBAzzBsyOcR+fFeV2UFpxlzyH8kPP2CQf0jZk=</latexit><latexit sha1_base64="zeWOiLSXOAiRgl4Nz8pGKBEB1T0=">AAAB6nicdZDNSgMxFIXv1L9a/6ou3QSL4KpMitjpriCCy4rWFtqhZNJMG5rJDElGKEMfwY0LRdz6RO58GzNtBRU9EPg4515y7w0SwbVx3Q+nsLK6tr5R3Cxtbe/s7pX3D+50nCrK2jQWseoGRDPBJWsbbgTrJoqRKBCsE0wu8rxzz5Tmsbw104T5ERlJHnJKjLVuLgd4UK64Vdd1McYoB1w/dy00Gl4NewjnkVUFlmoNyu/9YUzTiElDBdG6h93E+BlRhlPBZqV+qllC6ISMWM+iJBHTfjYfdYZOrDNEYazskwbN3e8dGYm0nkaBrYyIGevfWW7+lfVSE3p+xmWSGibp4qMwFcjEKN8bDbli1IipBUIVt7MiOiaKUGOvU7JH+NoU/Q93tSq2fH1WaXrLcxThCI7hFDDUoQlX0II2UBjBAzzBsyOcR+fFeV2UFpxlzyH8kPP2CQf0jZk=</latexit><latexit sha1_base64="zeWOiLSXOAiRgl4Nz8pGKBEB1T0=">AAAB6nicdZDNSgMxFIXv1L9a/6ou3QSL4KpMitjpriCCy4rWFtqhZNJMG5rJDElGKEMfwY0LRdz6RO58GzNtBRU9EPg4515y7w0SwbVx3Q+nsLK6tr5R3Cxtbe/s7pX3D+50nCrK2jQWseoGRDPBJWsbbgTrJoqRKBCsE0wu8rxzz5Tmsbw104T5ERlJHnJKjLVuLgd4UK64Vdd1McYoB1w/dy00Gl4NewjnkVUFlmoNyu/9YUzTiElDBdG6h93E+BlRhlPBZqV+qllC6ISMWM+iJBHTfjYfdYZOrDNEYazskwbN3e8dGYm0nkaBrYyIGevfWW7+lfVSE3p+xmWSGibp4qMwFcjEKN8bDbli1IipBUIVt7MiOiaKUGOvU7JH+NoU/Q93tSq2fH1WaXrLcxThCI7hFDDUoQlX0II2UBjBAzzBsyOcR+fFeV2UFpxlzyH8kPP2CQf0jZk=</latexit><latexit sha1_base64="zeWOiLSXOAiRgl4Nz8pGKBEB1T0=">AAAB6nicdZDNSgMxFIXv1L9a/6ou3QSL4KpMitjpriCCy4rWFtqhZNJMG5rJDElGKEMfwY0LRdz6RO58GzNtBRU9EPg4515y7w0SwbVx3Q+nsLK6tr5R3Cxtbe/s7pX3D+50nCrK2jQWseoGRDPBJWsbbgTrJoqRKBCsE0wu8rxzz5Tmsbw104T5ERlJHnJKjLVuLgd4UK64Vdd1McYoB1w/dy00Gl4NewjnkVUFlmoNyu/9YUzTiElDBdG6h93E+BlRhlPBZqV+qllC6ISMWM+iJBHTfjYfdYZOrDNEYazskwbN3e8dGYm0nkaBrYyIGevfWW7+lfVSE3p+xmWSGibp4qMwFcjEKN8bDbli1IipBUIVt7MiOiaKUGOvU7JH+NoU/Q93tSq2fH1WaXrLcxThCI7hFDDUoQlX0II2UBjBAzzBsyOcR+fFeV2UFpxlzyH8kPP2CQf0jZk=</latexit>

E2<latexit sha1_base64="59unTsKH7cOgF4GZtTkIjbTpXyM=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJETvdFURwWdHaQjuUTJppQzMXkoxQhj6CGxeKuPWJ3Pk2ZtoKKvpD4OP/zyHnHD+RQhuMP5zCyura+kZxs7S1vbO7V94/uNNxqhhvs1jGqutTzaWIeNsII3k3UZyGvuQdf3KR5517rrSIo1szTbgX0lEkAsGosdbN5aA2KFdwFWNMCEE5kPo5ttBouDXiIpJHVhVYqjUov/eHMUtDHhkmqdY9ghPjZVQZwSSflfqp5gllEzriPYsRDbn2svmoM3RinSEKYmVfZNDc/d6R0VDraejbypCasf6d5eZfWS81getlIkpSwyO2+ChIJTIxyvdGQ6E4M3JqgTIl7KyIjamizNjrlOwRvjZF/8NdrUosX59Vmu7yHEU4gmM4BQJ1aMIVtKANDEbwAE/w7Ejn0XlxXhelBWfZcwg/5Lx9Agl4jZo=</latexit><latexit sha1_base64="59unTsKH7cOgF4GZtTkIjbTpXyM=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJETvdFURwWdHaQjuUTJppQzMXkoxQhj6CGxeKuPWJ3Pk2ZtoKKvpD4OP/zyHnHD+RQhuMP5zCyura+kZxs7S1vbO7V94/uNNxqhhvs1jGqutTzaWIeNsII3k3UZyGvuQdf3KR5517rrSIo1szTbgX0lEkAsGosdbN5aA2KFdwFWNMCEE5kPo5ttBouDXiIpJHVhVYqjUov/eHMUtDHhkmqdY9ghPjZVQZwSSflfqp5gllEzriPYsRDbn2svmoM3RinSEKYmVfZNDc/d6R0VDraejbypCasf6d5eZfWS81getlIkpSwyO2+ChIJTIxyvdGQ6E4M3JqgTIl7KyIjamizNjrlOwRvjZF/8NdrUosX59Vmu7yHEU4gmM4BQJ1aMIVtKANDEbwAE/w7Ejn0XlxXhelBWfZcwg/5Lx9Agl4jZo=</latexit><latexit sha1_base64="59unTsKH7cOgF4GZtTkIjbTpXyM=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJETvdFURwWdHaQjuUTJppQzMXkoxQhj6CGxeKuPWJ3Pk2ZtoKKvpD4OP/zyHnHD+RQhuMP5zCyura+kZxs7S1vbO7V94/uNNxqhhvs1jGqutTzaWIeNsII3k3UZyGvuQdf3KR5517rrSIo1szTbgX0lEkAsGosdbN5aA2KFdwFWNMCEE5kPo5ttBouDXiIpJHVhVYqjUov/eHMUtDHhkmqdY9ghPjZVQZwSSflfqp5gllEzriPYsRDbn2svmoM3RinSEKYmVfZNDc/d6R0VDraejbypCasf6d5eZfWS81getlIkpSwyO2+ChIJTIxyvdGQ6E4M3JqgTIl7KyIjamizNjrlOwRvjZF/8NdrUosX59Vmu7yHEU4gmM4BQJ1aMIVtKANDEbwAE/w7Ejn0XlxXhelBWfZcwg/5Lx9Agl4jZo=</latexit><latexit sha1_base64="59unTsKH7cOgF4GZtTkIjbTpXyM=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJETvdFURwWdHaQjuUTJppQzMXkoxQhj6CGxeKuPWJ3Pk2ZtoKKvpD4OP/zyHnHD+RQhuMP5zCyura+kZxs7S1vbO7V94/uNNxqhhvs1jGqutTzaWIeNsII3k3UZyGvuQdf3KR5517rrSIo1szTbgX0lEkAsGosdbN5aA2KFdwFWNMCEE5kPo5ttBouDXiIpJHVhVYqjUov/eHMUtDHhkmqdY9ghPjZVQZwSSflfqp5gllEzriPYsRDbn2svmoM3RinSEKYmVfZNDc/d6R0VDraejbypCasf6d5eZfWS81getlIkpSwyO2+ChIJTIxyvdGQ6E4M3JqgTIl7KyIjamizNjrlOwRvjZF/8NdrUosX59Vmu7yHEU4gmM4BQJ1aMIVtKANDEbwAE/w7Ejn0XlxXhelBWfZcwg/5Lx9Agl4jZo=</latexit>

✓<latexit sha1_base64="N09dhHSwiX/uozYXpZqH3+Y2RpA=">AAAB7XicdZDLSgMxFIYz9VbrrerSTbAIrkpSxE53BTcuK9gLtEPJpJk2NnMhOSOUoe/gxoUibn0fd76NmbaCiv4Q+Pj/c8g5x0+UNEDIh1NYW9/Y3Cpul3Z29/YPyodHHROnmos2j1Wsez4zQslItEGCEr1ECxb6SnT96VWed++FNjKObmGWCC9k40gGkjOwVmcAEwFsWK6QKiGEUopzoPVLYqHRcGvUxTSPrCpopdaw/D4YxTwNRQRcMWP6lCTgZUyD5ErMS4PUiITxKRuLvsWIhcJ42WLaOT6zzggHsbYvArxwv3dkLDRmFvq2MmQwMb+z3Pwr66cQuF4moyQFEfHlR0GqMMQ4Xx2PpBYc1MwC41raWTGfMM042AOV7BG+NsX/Q6dWpZZvLipNd3WOIjpBp+gcUVRHTXSNWqiNOLpDD+gJPTux8+i8OK/L0oKz6jlGP+S8fQLt7Y9U</latexit><latexit sha1_base64="N09dhHSwiX/uozYXpZqH3+Y2RpA=">AAAB7XicdZDLSgMxFIYz9VbrrerSTbAIrkpSxE53BTcuK9gLtEPJpJk2NnMhOSOUoe/gxoUibn0fd76NmbaCiv4Q+Pj/c8g5x0+UNEDIh1NYW9/Y3Cpul3Z29/YPyodHHROnmos2j1Wsez4zQslItEGCEr1ECxb6SnT96VWed++FNjKObmGWCC9k40gGkjOwVmcAEwFsWK6QKiGEUopzoPVLYqHRcGvUxTSPrCpopdaw/D4YxTwNRQRcMWP6lCTgZUyD5ErMS4PUiITxKRuLvsWIhcJ42WLaOT6zzggHsbYvArxwv3dkLDRmFvq2MmQwMb+z3Pwr66cQuF4moyQFEfHlR0GqMMQ4Xx2PpBYc1MwC41raWTGfMM042AOV7BG+NsX/Q6dWpZZvLipNd3WOIjpBp+gcUVRHTXSNWqiNOLpDD+gJPTux8+i8OK/L0oKz6jlGP+S8fQLt7Y9U</latexit><latexit sha1_base64="N09dhHSwiX/uozYXpZqH3+Y2RpA=">AAAB7XicdZDLSgMxFIYz9VbrrerSTbAIrkpSxE53BTcuK9gLtEPJpJk2NnMhOSOUoe/gxoUibn0fd76NmbaCiv4Q+Pj/c8g5x0+UNEDIh1NYW9/Y3Cpul3Z29/YPyodHHROnmos2j1Wsez4zQslItEGCEr1ECxb6SnT96VWed++FNjKObmGWCC9k40gGkjOwVmcAEwFsWK6QKiGEUopzoPVLYqHRcGvUxTSPrCpopdaw/D4YxTwNRQRcMWP6lCTgZUyD5ErMS4PUiITxKRuLvsWIhcJ42WLaOT6zzggHsbYvArxwv3dkLDRmFvq2MmQwMb+z3Pwr66cQuF4moyQFEfHlR0GqMMQ4Xx2PpBYc1MwC41raWTGfMM042AOV7BG+NsX/Q6dWpZZvLipNd3WOIjpBp+gcUVRHTXSNWqiNOLpDD+gJPTux8+i8OK/L0oKz6jlGP+S8fQLt7Y9U</latexit><latexit sha1_base64="N09dhHSwiX/uozYXpZqH3+Y2RpA=">AAAB7XicdZDLSgMxFIYz9VbrrerSTbAIrkpSxE53BTcuK9gLtEPJpJk2NnMhOSOUoe/gxoUibn0fd76NmbaCiv4Q+Pj/c8g5x0+UNEDIh1NYW9/Y3Cpul3Z29/YPyodHHROnmos2j1Wsez4zQslItEGCEr1ECxb6SnT96VWed++FNjKObmGWCC9k40gGkjOwVmcAEwFsWK6QKiGEUopzoPVLYqHRcGvUxTSPrCpopdaw/D4YxTwNRQRcMWP6lCTgZUyD5ErMS4PUiITxKRuLvsWIhcJ42WLaOT6zzggHsbYvArxwv3dkLDRmFvq2MmQwMb+z3Pwr66cQuF4moyQFEfHlR0GqMMQ4Xx2PpBYc1MwC41raWTGfMM042AOV7BG+NsX/Q6dWpZZvLipNd3WOIjpBp+gcUVRHTXSNWqiNOLpDD+gJPTux8+i8OK/L0oKz6jlGP+S8fQLt7Y9U</latexit>

Compton Circle

E = E1 + E2

cos✓ = 1�mec2

✓1

E2� 1

E1 + E2

◆

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Previous experiments: COMPTEL and COSI!23

▶ 12 HPGe crystals (2x2x3), double-sided stripped ▶ energy range: 0.2 - 5 MeV ▶ spacial resolution: ~ 2mm3

▶ 1st balloon flight from Antarctica in 2014 ▶ 2nd flight from New Zealand in 2016

NASA

~1.6

m

NaI Crystal

Liquid Scintillator

~ 8cm

Z. Andreas

~ 8cm

▶ launched into space in 1991 ▶ installed on Compton Gamma-Ray Observatory ▶ energy range: 0.75 - 30 MeV ▶ spacial resolution: ~ 40cm3

▶ Detected ~30 sources

COMPTEL (The Imaging Compton Telescope)

COSI (The Compton Spectrometer and Imager)

LArTPC Detector!24

3D particle tracking in LArTPC ▶ Measure both scintillation light and

ionization electrons ▶ Scintillation light is detected in PMTs ▶ Ionization electrons drift and are

collected in anode wire planes

2 paths for scintillation light

PMT

PMT

PMT

e-e-

e-

e-e-e-

e-

PMT

PMT

PMT

Credit: Bo Yu

E-fie

ld, ~

500V

/cm

Anode wire planes (U, V, Y)

Cathode Plane

Ar2+Ar+ Ar2*

Ionization Ionized Molecule

e- Recombination

~1600ns

Ar* Ar2*

Excitation Excited Molecule Ar

Ar

Scintillation light Vacuum UV (128nm)

~6ns

Ar

LArTPC DETECTORS HAVE BEEN WELL-STUDIED AND WIDELY-USED FOR LARGE-SCALE NEUTRINO/DARK MATTER SEARCH EXPERIMENTS

xY

Z

Plastic Scintillators : Veto incoming charged particles LArTPC : Compton camera and calorimeter (for pair-production)

▶ Scintillation light at SiPMs to trigger events ▶ Wires/pads on anode plane (X, Y), drift time (Z) to provide a 3D image/track

Signal localized by segmentation to reduce coincident background Neutron events can be separated based on the pulse shape

!25GRAMS Detection Concept: MeV Gamma-rays

LArTPC

TOF Plastic Scintillator

SiPMs

Anode wires/pads (X-Y plane)

E-FI

ELD

Segmentation

e-e-

e+ e-

Gamma-Ray Pair Production Event

e-

e- θ

Gamma-Ray Compton Scattering Event

Charged Particle

e-

LARTPC DETECTOR SURROUNDED BY PLASTIC SCINTILLATORS LARTPC MEASURES SCINTILLATION LIGHT AND IONIZATION ELECTRONS

event Reconstruction for Compton Scattering!26




Compton Circle

Photoabsorption

Compton ScatteringE1

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Compton Circle

E3<latexit sha1_base64="WVWhqGegG9Ug8AUOaxqbgGYyzhs=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJFTvdFURwWdFeoB1KJs20oZkLSUYopY/gxoUibn0id76NmbaCiv4Q+Pj/c8g5x0+k0AbjDye3srq2vpHfLGxt7+zuFfcPWjpOFeNNFstYdXyquRQRbxphJO8kitPQl7ztjy+zvH3PlRZxdGcmCfdCOoxEIBg11rq96p/1iyVcxhgTQlAGpHqBLdRqboW4iGSRVQmWavSL771BzNKQR4ZJqnWX4MR4U6qMYJLPCr1U84SyMR3yrsWIhlx70/moM3RinQEKYmVfZNDc/d4xpaHWk9C3lSE1I/07y8y/sm5qAtebiihJDY/Y4qMglcjEKNsbDYTizMiJBcqUsLMiNqKKMmOvU7BH+NoU/Q+tSplYvjkv1d3lOfJwBMdwCgSqUIdraEATGAzhAZ7g2ZHOo/PivC5Kc86y5xB+yHn7BAr8jZs=</latexit><latexit sha1_base64="WVWhqGegG9Ug8AUOaxqbgGYyzhs=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJFTvdFURwWdFeoB1KJs20oZkLSUYopY/gxoUibn0id76NmbaCiv4Q+Pj/c8g5x0+k0AbjDye3srq2vpHfLGxt7+zuFfcPWjpOFeNNFstYdXyquRQRbxphJO8kitPQl7ztjy+zvH3PlRZxdGcmCfdCOoxEIBg11rq96p/1iyVcxhgTQlAGpHqBLdRqboW4iGSRVQmWavSL771BzNKQR4ZJqnWX4MR4U6qMYJLPCr1U84SyMR3yrsWIhlx70/moM3RinQEKYmVfZNDc/d4xpaHWk9C3lSE1I/07y8y/sm5qAtebiihJDY/Y4qMglcjEKNsbDYTizMiJBcqUsLMiNqKKMmOvU7BH+NoU/Q+tSplYvjkv1d3lOfJwBMdwCgSqUIdraEATGAzhAZ7g2ZHOo/PivC5Kc86y5xB+yHn7BAr8jZs=</latexit><latexit sha1_base64="WVWhqGegG9Ug8AUOaxqbgGYyzhs=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJFTvdFURwWdFeoB1KJs20oZkLSUYopY/gxoUibn0id76NmbaCiv4Q+Pj/c8g5x0+k0AbjDye3srq2vpHfLGxt7+zuFfcPWjpOFeNNFstYdXyquRQRbxphJO8kitPQl7ztjy+zvH3PlRZxdGcmCfdCOoxEIBg11rq96p/1iyVcxhgTQlAGpHqBLdRqboW4iGSRVQmWavSL771BzNKQR4ZJqnWX4MR4U6qMYJLPCr1U84SyMR3yrsWIhlx70/moM3RinQEKYmVfZNDc/d4xpaHWk9C3lSE1I/07y8y/sm5qAtebiihJDY/Y4qMglcjEKNsbDYTizMiJBcqUsLMiNqKKMmOvU7BH+NoU/Q+tSplYvjkv1d3lOfJwBMdwCgSqUIdraEATGAzhAZ7g2ZHOo/PivC5Kc86y5xB+yHn7BAr8jZs=</latexit><latexit sha1_base64="WVWhqGegG9Ug8AUOaxqbgGYyzhs=">AAAB6nicdZDLSgMxFIbP1Futt6pLN8EiuCpJFTvdFURwWdFeoB1KJs20oZkLSUYopY/gxoUibn0id76NmbaCiv4Q+Pj/c8g5x0+k0AbjDye3srq2vpHfLGxt7+zuFfcPWjpOFeNNFstYdXyquRQRbxphJO8kitPQl7ztjy+zvH3PlRZxdGcmCfdCOoxEIBg11rq96p/1iyVcxhgTQlAGpHqBLdRqboW4iGSRVQmWavSL771BzNKQR4ZJqnWX4MR4U6qMYJLPCr1U84SyMR3yrsWIhlx70/moM3RinQEKYmVfZNDc/d4xpaHWk9C3lSE1I/07y8y/sm5qAtebiihJDY/Y4qMglcjEKNsbDYTizMiJBcqUsLMiNqKKMmOvU7BH+NoU/Q+tSplYvjkv1d3lOfJwBMdwCgSqUIdraEATGAzhAZ7g2ZHOo/PivC5Kc86y5xB+yHn7BAr8jZs=</latexit>

Photoabsorption

Compton Scattering

Compton Scattering

✓0<latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit><latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit><latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit><latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit>

Compton Scattering




Compton Circle

Compton Scattering

Compton Scattering

✓0<latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit><latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit><latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit><latexit sha1_base64="acfBVDD4iQ0gWKDpAVP970Fy8oo=">AAAB7nicdZDLSgMxFIYz9VbrrerSTbCIrsqkiJ3uCm5cVrAXaIeSSTNtaCYzJGeEMvQh3LhQxK3P4863MdNWUNEfAh//fw455wSJFAZc98MprK1vbG4Vt0s7u3v7B+XDo46JU814m8Uy1r2AGi6F4m0QIHkv0ZxGgeTdYHqd5917ro2I1R3MEu5HdKxEKBgFa3UHMOFAz4flilt1XZcQgnMg9SvXQqPh1YiHSR5ZVdBKrWH5fTCKWRpxBUxSY/rETcDPqAbBJJ+XBqnhCWVTOuZ9i4pG3PjZYtw5PrPOCIextk8BXrjfOzIaGTOLAlsZUZiY31lu/pX1Uwg9PxMqSYErtvwoTCWGGOe745HQnIGcWaBMCzsrZhOqKQN7oZI9wtem+H/o1KrE8u1lpemtzlFEJ+gUXSCC6qiJblALtRFDU/SAntCzkziPzovzuiwtOKueY/RDztsnUHiPhQ==</latexit>

E = E1 + E2 + E3

cos✓ = 1�mec2

✓1

E2 + E3� 1

E1 + E2 + E3

◆

cos✓0 = 1�mec2

✓1

E3� 1

E2 + E3

◆

<latexit sha1_base64="30mbvJiKy62b0ryWfH2sBdpGhx4=">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</latexit><latexit sha1_base64="30mbvJiKy62b0ryWfH2sBdpGhx4=">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</latexit><latexit sha1_base64="30mbvJiKy62b0ryWfH2sBdpGhx4=">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</latexit><latexit sha1_base64="30mbvJiKy62b0ryWfH2sBdpGhx4=">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</latexit>

E = E1 + E2 + E03

cos✓ = 1�mec2

✓1

E2 + E03

� 1

E1 + E2 + E03

◆

E03 = �E2

2+

sE2

2

4+

E2mec2

1� cos✓0<latexit sha1_base64="Vi6mxlNmuFqSIdJC5AC8l+sdbBc=">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</latexit><latexit sha1_base64="Vi6mxlNmuFqSIdJC5AC8l+sdbBc=">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</latexit><latexit sha1_base64="Vi6mxlNmuFqSIdJC5AC8l+sdbBc=">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</latexit><latexit sha1_base64="Vi6mxlNmuFqSIdJC5AC8l+sdbBc=">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</latexit>

One Compton Scattering + Photoabsorption

Two Compton Scatterings + Photoabsorption

Three Compton Scatterings + Escaping Photon

E = E1 + E2

cos✓ = 1�mec2

✓1

E2� 1

E1 + E2

◆

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Compton “Event Circles”

LARTPC vs. semiconductor detector!27

LArTPC Semiconductor (Si/Ge)

ρ (g/cm3) 1.4 2.3/5.3

Toperation ~80K ~240K/~80K

Cost $ $$$

Signal scintillation light + Ionization electrons electrons, holes

X, Y Positions wires on anode plane (X-Y) double-sided strips

Z position from drift time from layer #

# of Layers 1 layer multi-layers

# of Electronics # ###

Dead Volume almost no dead volume detector frame, preamps

Neutron bkg Identified with pulse shape No rejection capability

LArTPC Semiconductor Detector (Si/Ge)Anode wires/pads

SiPMs LArTPC

Si/Ge Preamp Frame

LARTPC IS COST-EFFECTIVE AND EASILY EXPANDABLE TO A LARGER-SCALE, MUCH LESS CHANNELS/ELECTRONICS REQUIRED, ALMOST NO DEAD VOLUME

xY

Z

GRAMS Effective Area!28

Selection Cuts ▶ Compton scattering : interaction points should be separated by > 10cm ▶ Pair production : both e+ and e- should stop within detector, leave tracks > 2cm

LArTPC: 140cm x 140cm x 20cm

Possible detector upgrade Finer pitch of anode wires/pads Calorimeter around LArTPC

GRAMS MeV Gamma-ray Continuum sensitivity!29

SINGLE BALLOON FLIGHT: AN ORDER OF MAGNITUDE IMPROVED SATELLITE MISSION: COMPARABLE (BETTER) TO FUTURE MISSIONS

Takahashi et al., 2013


Current Status and Future Prospects

GRAMS Collaboration!31

Tsuguo Aramaki, SLAC GAPS, SuperCDMS

GRAMS antimatter search

Hirokazu Odaka, U of Tokyo Astro-H, Suzaku

GRAMS event reconstruction

Georgia Karagiorgi, Columbia U MicroBooNE, SBND, DUNE

GRAMS LArTPC design

Yoshiyuki Inoue, RIKEN Astrophysics theorist (AGN etc.) GRAMS MeV gamma-ray science

Charles Hailey: professor at Columbia U, GAPS PI, NuSTAR Co-I Pelle Hansson: former SLAC physicist/engineer, ATLAS, SuperCDMS, DUNE

Possible Future Collaborations SLAC DUNE, LZ , Stanford nEXO , MIT/UCLA/UCSD/Hawaii GAPS , Columbia theory group …

First collaboration meeting in July 2019 at Columbia University, Nevis Lab

TimeScale!32

“Event Circle” becomes “Event Arc”

Submitted proposals to NASA APRA, SLAC LDRD programs

R&D FOR PROOF OF CONCEPT – IN A FEW YEARS ▶ Validate detection concept ▶ Develop event reconstruction technique

FIRST BALLOON FLIGHT (STARTING WITH AN ENGINEERING FLIGHT) - IN 5-10 YEARS ▶ MeV gamma-ray observations

▶ Focusing on bright objects, Nuclear lines ▶ Antimatter-based indirect DM search

▶ Possibly detect antideuterons from DM in the first flight ▶ Investigate Fermi/AMS-02 results

TPC DESIGN UPGRADE/DEVELOPMENT - IN 10 YEARS ▶ Improve energy/position resolutions, event reconstruction

▶ Finer pitch of anode wires/pads to track Compton scattered electrons ▶ Add calorimeters to improve the performance of Energy measurement

SATELLITE MISSION - IN > 10 YEARS ▶ All sky survey in the MeV energy domain ▶ Antimatter-based (including antihelium) DM search

Summary!33

▶ GRAMS is the first experiment to target both gamma-ray observations in the poorly explored MeV energy band and antimatter-based dark matter search.

▶ With a cost-effective, large-scale LArTPC detector, the sensitivity to MeV gamma rays can be more than an order of magnitude improved compared to previous experiments.

▶ GRAMS antideutron measurements can provide essentially background-free dark matter signatures while deeply investigating and validating the possible dark matter detection indicated in Fermi GCE and AMS-02 antiproton excess.

▶ The project is currently in the R&D phase and will demonstrate the detection concept using a small-scale prototype detector, MiniGRAMS.

▶ Project will then become a balloon experiment, as a step forward to a satellite mission with detector upgrades.

▶ GRAMS detector technology can also be applicable to other fields, such as nuclear medicine and homeland security.

the grams project · tsuguo aramaki, slac ipmu apec seminar july 22nd 2019 the grams project dual...

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