11 Sept, 2021
TGSW2021(Universe Evolution and Matter Origin) @ Online

Accelerator-based physics experiments
pioneered by superconducting TES
microcalorimeters
SDD(FWHM ~ 150 eV)TES(FWHM ~ 5 eV)@ ~ 6 keV

Shinji OKADA (Chubu Univ.)

2

HEATES project=
High-resolution Exotic Atom x-ray spectroscopy with TES
negative chargedμ-

μ- : Muon
π- : Pion
K- : Kaon …

TES microcalorimeterμ-(Cryogenic detector)

X-raysZ+
nucleusnamed after microcalorimeter
being a heat measuring device

having high resolution

3

HEATES project=
High-resolution Exotic Atom x-ray spectroscopy with TES
launched in 2013
collaborating with NIST (US)2014

π- atom @ PSI (Switzerland)

Feasibility
study

K- atom @ J-PARC (Japan)

Study ofstrong KN
interaction

2016

2018

2020

μ- atom @ J-PARC (Japan)

Study of
BSQED

Bound-State Quantum ElectroDynamics

under extremely strong
electric fields

2022

μ- molecule
X-ray spectroscopy for 30 ~ 100 keV

future…

4

Collaboration (Muonic atom)
J-PARC MLF 2019MS01 collaboration (for 2020-Jan run)Shinji Okada

Chubu Univ.

Yuto

Ichinohe

Pietro Caradonna

ShinyaYamadaMiho Katsuragawa

Yasushi

Kino

KenichiOkutsuKairi Mine

IPMU

Tadayuki Takahashi

Ryota

Shinichiro Takeda
Tadashi Hashimoto
Takahito Osawa
Shin Watanabe

JAEA

Hideyuki

TatsunoIndelicato
Paul

KEK

Patrick Strasser

Japan

CNRS

FranceNIST

USWilliam B. Doriese
Malcolm S. Durkin

Osaka Univ.

Gene C. Hilton

Hirofumi Noda

Kelsey M. Morgan

Toshiyuki Azuma

Galen C. O'Neil
Carl D. Reintsema

TadaAki Isobe

Yasuhiro Ueno

Tokyo
Metropolitan
Univ.

Johnathon D. Gard

I Huan Chiu

Takuma Okumura

Japan

Joseph W. Fowler

Soshi Takeshita

Sohtaro Kanda

Tohoku Univ.

Douglas A. Bennett

Yasuhiro Miyake

Kazuhiko Ninomiya

Suda

Nancy

Naritoshi Kawamura
Kouichiro Shimomura

Hirotaka
Paul

JAXA

Hayakawa

Rikkyo Univ.

RIKEN

Dan R. Schmidt
Daniel S. Swetz
Joel N. Ullom

Particle, Nuclear, Hadron, Atomic physicists + Astro physicists + TES experts
interdisciplinary teamContents
1. Introduction
2. What’s TES microcalorimeter
3. Experiment
4. Results of muonic Neon experiment
5. Serendipity
6. Summary-> interesting phenomena discovered by chance
during detector study6

1. Introduction

sha1_base64="WbUN5NGOFpodPYLQGpFXUT6/lyw=">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</latexit>

sha1_base64="WbUN5NGOFpodPYLQGpFXUT6/lyw=">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</latexit><latexit

sha1_base64="WbUN5NGOFpodPYLQGpFXUT6/lyw=">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</latexit><latexit

sha1_base64="WbUN5NGOFpodPYLQGpFXUT6/lyw=">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</latexit><latexit<latexit

sha1_base64="zllwRJJeyCphcExxCrCCVu/L3Mw=">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</latexit>

sha1_base64="zllwRJJeyCphcExxCrCCVu/L3Mw=">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</latexit><latexit

sha1_base64="zllwRJJeyCphcExxCrCCVu/L3Mw=">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</latexit><latexit

sha1_base64="zllwRJJeyCphcExxCrCCVu/L3Mw=">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</latexit><latexit<latexit

Muonic atome-deexcitation
processZ+

nucleusμ-μ

Excited state

when generated at electron K-shell
s
m⇤µ
n/
⇠ 14
me

…

8

when a negative muon
stopped in a target material,
muonic atom is generated

muon (as heavy electron)e- mass : 0.511 MeV/c2
μ- mass : 105.7 MeV/c2

meRadius / m⇤µm⇤µ
X-ray energy / me

x 1/200
x 200

c.f. H atom (2p-1s) 122nm ~ 10 eV
μH atom (2p-1s) ~ 2 keV9Strong electric fielde-deexcitation
processμ-✓ muon feel an extremely strong electric field➡ internal electric field strength is to be 2002(=40,000) times higher than that of normalhydrogen-like ions.
➡ an ideal probe to explore QED“under extremely strong electric fields”

strongelectric
field

Z+
nucleus

μinversely
proportional to
the square of
the radius.

X-rayshigh-precision
spectroscopy

Internal electric field of muonic atom [V/m]Internal electric field [V/m]Internal electric field
N Ne

23

10

Ar

Kr

Xe

∝

Z3

Pb

U

10

1022
1021
1020
1019
Schwinger Limit :1.32 x 1018 [V/m]18

10

where the electric field
becomes nonlinear in QED

17

10

normal hydrogen-like ion : n = 1

16

10

1015
1014
1013
1012
0

10

20

30

40

50

60

70
80
90
Atomic number Z

Atomic number Z

Atomic unit ofelectric field :5.14 x 1011 [V/m]strong electric field @ heavier atoms → still lower than Schwinger limit

Internal electric field of muonic atom [V/m]Internal electric field [V/m]Internal electric field : x 2002
N Ne

23

10

Ar

Kr

Xe

Pb

11

U

1022

muonic atom : n = 1

1021
1020

x 40,000

1019

Schwinger Limit :1.32 x 1018 [V/m]

18

10

1017

normal hydrogen-like ion : n = 1

16

10

1015
1014
1013
1012
0

10

20

30

40

50

60

70
80
90
Atomic number Z

Atomic number Z

Atomic unit ofelectric field :5.14 x 1011 [V/m]12

Avoiding nuclear-size eﬀect
Internal electric field of muonic atom [V/m]

N Ne

23

10

Ar

Kr

Xe

Pb

U

n=1

22

10

n=2
n=3
n=4

1021
1020

LargerNuclearsize
eﬀect
Smaller....

Internal electric field [V/m]principal quantum number
for μ atoms

1019
1018
1017
1016
1015
1014
1013

✓ But, in 12the Lower “n” (principal quantum number) state, nuclear size eﬀect10(overlapping with nucleus) become dominant.
0

10

20

30

40

50

60

70
80
90
Atomic number Z➡ Carefully choose X-ray transition into the energy level where the nuclear
Atomic number Z
size eﬀect is negligible but having significant QED eﬀect

13

Muonic Ne 5→4 X-ray
Internal electric field of muonic atom [V/m]

N Ne

23

10

Ar

Kr

Xe

Pb

U

n=1 for μ atoms/ions

1022

1020

n=2
n=3
n=4
n=4

1019

....

Internal electric field [V/m]

The first experiment (with ~10 keV X-ray region)

1021

Schwinger Limit :1.32 x 1018 [V/m]

18

10

1017

U

1016
1015
1014

Nucl. size eﬀect

μNe 5→4

13

10~ 6 keV

12

10

0

10

20

30

40

50

60

70
80
90
Atomic number Z

原子番号 Z

14

Low pressure gas targete-Auger electrons

deexcitation
processμ-Z+
nucleusμ-✓ the muon peels oﬀ most (or all) of electrons
bound to the nucleus as Auger electrons➡ a highly-charged muonic atom isolated in
vacuum are generated✓ Low density gas target is required to avoid
rapid refilling of electrons into this system fromsurrounding atoms.

efrom
surroundingatoms

Problems so far
1. Electron refill ：➡ To avoid rapid refilling of electrons from the surrounding atoms,
a low-density gas target (e.g., as low as 0.1 atom) is essential➡ However, it is experimentally diﬃcult to eﬃciently stopmuons in a low-density target due to their large momentum
distribution (Δp/p ~ several %) via traveling pion decay.

2. X-ray detector :➡ need both “high resolution” and “large eﬀective area”

15

This project
1. High-intensity low-energy negative muon
➡ world strongest pulse low-energy μ- source @ J-PARC
MUSE (muon facility)➡ isolated muonic atoms in vacuum is available by using
low-density gas target

2. Novel superconducting detector➡ an array of NIST’s multi-pixel TES microcalorimeters➡ combining both “high resolution” and “large eﬀective area”

16

2. What’s TESTES microcalorimeter18

Microcalorimeter
super
conducting
stateparticles
Photon1. incident particles absorbed
2. Energy ΔE -> Phonon
3. Tiny temperature rise ismeasured by a highly sensitive
temperature sensor TES

Reference : Bennet et al., Rev. Sci. Instrum. 83, 093113 (2012)

20

TES microcalorimeterTransition Edge Sensor

Microcalorimeterparticles

R0~50 mΩnormalconducting
state

Resistancesuper
conducting
stateﬁxed at the transitionedge by applying
constant voltage bias

bias point
R0/RN~0.2

Reference : Bennet et al., Rev. Sci. Instrum. 83, 093113 (2012)

21

TES microcalorimeterTransition Edge Sensor

Microcalorimeterparticles

R0~50 mΩResistancesuper
conducting
stateparticleabsorption

Rapid increase
in resistancebias point
R0/RN~0.2

Typicalpulseτrise~L/(Rsh+R0)
τfall~C/G

rise time ~ 200 µs
decay time ~ 500 µs

Tiny temperature risehigh energy resolution (ΔE / E ~ 10-3)
TES : ΔE (FWHM) ~ 5 eV @ 6 keV X-ray(ref. SDD : ΔE (FWHM) ~ 150 eV @ 6 keV)
Reference : Bennet et al., Rev. Sci. Instrum. 83, 093113 (2012)

22

TES microcalorimeter
Microcalorimeter
super
conducting
stateTransition Edge Sensor

particles
R0~50 mΩbias current
constant
bias

1. incoming radiation
2. temperature rise-> increasing resistance
3. reducing bias current

bias point
R0/RN~0.2

Read reduction of bias current
using SQUID

Typicalpulseτrise~L/(Rsh+R0)
τfall~C/G

rise time ~ 200 µs
decay time ~ 500 µs

22

TES microcalorimeter
Microcalorimeter
super
conducting
stateTransition Edge Sensor

particles
R0~50 mΩbias current
constant
bias

1. incoming radiation
2. temperature rise-> increasing resistance
3. reducing bias current
4. reducing Joule heat
5. temperature fall
6. back to original position

Read reduction of bias current
using SQUID

bias point

Typicalpulseτrise~L/(Rsh+R0)
τfall~C/G

negative
electro-thermal
feedback

R0/RN~0.2

rise time ~ 200 µs
decay time ~ 500 µs

23

TES microcalorimeter
Microcalorimeter
super
conducting
stateTransition Edge Sensor

particles
R0~50 mΩDynamic range( C/α)

bias point
R0/RN~0.2

Temp. sensitivity :Energy resolution :p
E / Tc2 C/↵I

Saturation energy : Esat ⇡ 4TC C/↵I

Typicalpulseτrise~L/(Rsh+R0)
τfall~C/G

rise time ~ 200 µs
decay time ~ 500 µs

Adiabatic Demagnetization Refrigerator (ADR)✓ Cooled down to 70 mK with ADR & pulse
two-stage
pulse tube
(60K, 3K)

50 mK cryostat(model : HPD 102 DENALI)(double-stage salt pills : GGG 1K, FAA 50mK)

ADR hold time > 1 day(< 500 mK @ GGG)

relatively
compact
size
33 cm

TES
chip

Photo credit : J. Uhlig

1cm

24

25

TES array (NIST)✓ 1 pixel : 300 x 320 um2 (~ 0.1 mm2)
✓ Mo-Cu bilayer TES✓ 4-µm-thick Bi absorber (eﬀ.~ 85% @ 6 keV)

photo credit:
D.R. Schmidt✓ 240 pixels✓ 23 mm2 eﬀ. area

small pixel size -> multi-pixel array

Time division SQUID multiplexing (TDM)
to reduce the number of wires running to the low-temperature stages of the cryocooler-> 240 pixel readout

The
NIST
TDM
architecture
only 8 read-out lines (8 columns)…

Eachcoloredblock is
1 pixelindependent 30ch
switching each 240ns(30 rows)…

master clock
125 MHz

NSLS
Users Meeting:May[kHz]21, 2008
multiplexing flame time : 7.2 [µs] (=240 ns x 30 ch) ->sampling
rate=139

Randy Doriese (NIST), NSLS Users Meeting: May 21, 2008

26

Example of pionic atom experiment
Counts / 1 [eV]@ PSI πM1 beamline

π-

Fe Fe
.њ2 .њ1

(c)

be

am

300
200

TES

resolution~ 7 eV -12C 4f-3d
 -12C 4d-3p

100

TES
arrays

SDD

200
Counts / 10 [eV]

X-ray tube
for energy
calib.

0

160
120

(d)

SDD

resolution~165 eV80
40
0

S. Okada et al., PTEP 2016, 091D01 (2016)

6.3

6.4

6.5
X-ray energy [keV]27

3. Experiment

29

J-PARCJapan Proton Accelerator Research Complex
Linac

Rapid Cycle Synchrotron
3-GeV synchrotron

Neutrino beam to Kamioka

Energy: 3GeV
Repetition 25Hz
Power: 500kW -> soon 1MW

MLF
Material & Life Science Facility

Muon Science Facility

Main Ring

providing high intensity
The 25th J-PARC PAC
proton beam

30-GeV synchrotron— 1.6 km ring —(c.f. 27 km @ LHC)

30

Muon beamline
J-PARC MUSE D2 beamline• 3 GeV proton beam → higher π- yieldπ-• avoiding window (@ solenoid magnet)→ higher μ- yield at lower energy region

π- → μ- + νμμ-Experimental area

31

Experimental setup
connected
to beam pipe
ɤILHT

3D view
Kaptonwindows

ADR
ɤ5L
X-raysTES
Be
window

Acrylic flange

ADR

calib. X-rays

Targetgas

X-ray
generator

ɤILHT
SDDs

X-ray
generator

4. Results

33

Energy calibration
Continuous X-ray irradiation during experiment✓controllable intensity✓many x-ray lines

Cu Cr Co

pure metals
as secondary target
ary Cr,Co
d
n
o
c
se
x-rays

X-ray tube

highenergyx-raysWelectron
μNeelectron gun

Energy resolution ~ 5 eV @ 6.9 keV

34

Energy vs. Timing (muon arrival time)35

Muonic-atom X-ray spectrum

36

37

Eﬀect of charged particle

荷電粒子による影響

Charged particles scattered at the timing¾ the muon beamの may hit theで、散乱さof
detector.た荷電粒子が検出器に飛び込む可能性がある。
Si baseChargedparticle

X-ray
Co Kα

shift to theにより、
high energy
高側にside bypileuppileupMuonic Ne atom 5→4 @ 0.1 atm
Preliminary

38

40

Internal electric field of muonic atom [V/m]

N Ne

23

10

Ar

Kr

Xe

Pb

U

n=1 for μ atoms/ions

1022

n=2
n=3
n=4
n=4

1021
1020
1019

....

Internal electric field [V/m]Next target?

82 keV

Schwinger Limit :1.32 x 1018 [V/m]18

10

20 keV

1017

U

1016

μAr 4→3~ 44 keV

1015
1014

μNe 5→4

13

10~ 6 keV

12

10

0

10

20

30

40

50

60

70
80
90
Atomic number Z

Atomic number Z

Atomic unit ofelectric field :5.14 x 1011 [V/m]R

Thermometer
sensitivity
using the sharptransition
betweennormalandWidthof transitionedge
supernormala few mKd ln Rsuperconducting ΔE~
state
to sensethetemperature
conducting
conducting102 3 E =ResistanceResistanceTES under developmentsated ln Tsate( Johnson noise and phonon noise are
the most fundamental )Energy resolution (σ)
Thermometer sensitivity
Dynamic range
kB T 2 C
normal d ln R 102 3
Emax CTC /E=
conductingdlnT0Temperature Trade-off between dynamic range and~100
mK
energy resolution : ΔE ~ √E
sate
( Johnson noise and phonon noise are
the most fundamental )Energyresolution--> developedby Stanford/ NIST at (σ)
the beginningapplications : astrophysics (space sate
Dynamic
range
kB T 2 C
normalE=
Emax CTC /conducting
Trade-off
between dynamic range andsate~ 100 mK Temperature( Johnson noise and phononnoise areenergy resolution : ΔE ~ √E

Width of transition edge
ΔE~ a few mKsuperconducting
satesuperconducting
0
sate

max

the most fundamental )max--> developed by Stanford / NIST at the beginning

0

kB T 2 C 41

~ 100 mK Temperature--> developed by Stanford / NIST at the beginning

Dynamicapplications
range : astrophysics (space satellite) etc.
Emax CTC /Trade-off between dynamic range andenergy resolution : ΔE ~ √Emax

applications : astrophysics (space satellite) etc.

✓New cryostat, readout system✓Available in a few years (for μ-atoms)✓Multiple units can be installed5. Serendipity

during TES detector study
connected
to beamline pipe

muon

Just for a study of energy shifts at
beam timing :Kapton windows
Air gap

ADR

TES

Observing characteristic X-rays frompure metal (Fe) excited by the
charged particles of the beam

Calib.
X-rays

Fe foilFe
ɤ-L
Kα
X-raysThis is what we expected

Be window

・

X-ray
generator

Vacuumchamber
Acrylic flange

・

・
・

・

・

43

Serendipity !
connected
to beamline pipe

muon
Kapton windows
Air gap

ADR

TES

Surprisingly,
other than Fe Kα and Kβ,
an unexpected and very broad
structure was discovered.

Calib.
X-rays

Fe foilFe
ɤ-L
Kα
X-rays

Structure is starting from Mn line?

Be window
X-ray
generator

Vacuumchamber
Acrylic flange44?
?
hypersatellite?

Serendipity !
Thanks to the high-resolution detector,
this structure could be observed.
TES(ΔE~5 eV)
SDD
(ΔE~150 eV)

hypersatellite45

Fe behaves like Mn with a charge of -1
Muonic Fe atom (μ- Fe)

X-rayelectron orb

Periodic table

ital
ee-

μ-

screeningFeμ-muon orbital

deexcitation
process✓Fe charge (+26) is shielded by μ- (-1)
✓From the standpoint of an electron, it looks
like Manganese with atomic number +25.
✓The degree of shielding changes during thedeexcitation of muon atoms✓This precise spectroscopy of electron X-ray
energy captured the whole picture of
muon's atomic formation process.

46

y

mto
ugy
y,
y
rs
s,
a-

Results (PRL 127(2021) 053001)
X-ray energy changes
depending on:

principal quantum numberof μ-atom
ミュオン原子の主量子数

rd
h
ror
i].
n
re
nct
he
el
ay
cd
ys
s.
as
he
n

1. Shielding eﬀect by muons(-> principal quantum numberof μFe)
電子L殻の穴数

FIG. 2. (a) X-ray spectrum in the energy range from 5000
to 7400 eV measured by the TES detector. Broad electronic
Kα and Kβ x rays from µFe are observed. In addition, sharp
Mn Kα1 and Kβ1, 3 x rays are identified (dotted lines). The
Mn Kα2 x rays are discernible at the low-energy side of the
Mn Kα1 line. Muonic x rays from µBe (n = 3 → 2) are
due to direct muon injection into a Be window in front of
the detector. A broad tail-like structure beneath the peak ofmuonic x rays from µBe is identified as the hypersatellite K h α
x rays. The energy of Mn K h α is also shown [46]. Cr and Co
Kα x rays are calibration x rays from the x-ray generator. Fe
Kα and Kβ x rays are due to direct injection of muons and2. Electron configuration（-> number of L-shell hole)

47

y

mto
ugy
y,
y
rs
s,
a-

Results (PRL 127(2021) 053001)
X-ray energy changes
depending on:

principal quantum numberof μ-atom

rd
h
ror
i].
n
re
nct
he
el
ay
cd
ys
s.
as
he
n

1. Shielding eﬀect by muons(-> principal quantum numberof μFe)number of
L-shell hole

FIG. 2. (a) X-ray spectrum in the energy range from 5000
to 7400 eV measured by the TES detector. Broad electronic
Kα and Kβ x rays from µFe are observed. In addition, sharp
Mn Kα1 and Kβ1, 3 x rays are identified (dotted lines). The
Mn Kα2 x rays are discernible at the low-energy side of the
Mn Kα1 line. Muonic x rays from µBe (n = 3 → 2) are
due to direct muon injection into a Be window in front of
the detector. A broad tail-like structure beneath the peak ofmuonic x rays from µBe is identified as the hypersatellite K h α
x rays. The energy of Mn K h α is also shown [46]. Cr and Co
Kα x rays are calibration x rays from the x-ray generator. Fe
Kα and Kβ x rays are due to direct injection of muons and2. Electron configuration（-> number of L-shell hole)48

yResults (PRL 127(2021) 053001)

principal quantum numberof μ-atom

rd
h
ror
i].
n
re
nct
he
el
ay
the moment of x-ray emission, which
colution of the de-excitation dynamics.
dcontributions, we calculated the enys
the electronic K x rays employing電子L殻
the
の穴数
s.
eveloped
for highly charged hollow ions
allic materials [49]. We calculated theas
Fe in vacuum with non-relativistic denheeory
an optimized effective poten4n andFIG. 2. (a) X-ray spectrum in the energy range from 5000

he self-interaction corrections [50]. We
to moving
7400 eVinmeasured
bypotenthe TES detector. Broad electronic
on to bean effective
Kα andrays from µFe
mthe nucleus
andKβ
thexsurrounding
elec-are observed. In addition, sharp
Kα1
Kβ1, 3 xrays are identified (dotted lines). The
toctrons Mn
movinginand
an effective
potential
Mn Kα2
x rays are discernible
self-consistently.
The num- at the low-energy side of the
u-the muon,
Mn Kα1line. Muonic
x rays from µBe (n = 3 → 2) are
nfigurations
with different
muon statesgydue
to K-,
directmuon
injection
into a Be window in front ofpancies
in
the
L-,
and
M
-shellsisy,the detector.
broad tail-like
he K x-ray
energies areAobtainedby the structure beneath the peakhof
yrays from µBe
is identified as the hypersatellite K α
ence ofmuonic
the twoxconfigurations
involvedhrsWe found
α is also shown [46]. Cr and Co
x rays.
of Mn KefthatThethe energy
outer screening
Kα
x raysareimportantcalibration
rays fromthe x-ray generator.
s,also reproduces“hyper-satellite
x-ray” Feundingmetal
is less
forxtheKαKβbandx raysareduetheto double
direct injectionof muons andabecause
the andvalenceformedbythefrom
K-hole state

X-ray energy changes
depending on:
1. Shielding eﬀect by muons(-> principal quantum number
4of μFe)2. Electron configuration（-> number of L-shell hole)Cascade calculation
reproduces spectrumwith ONLY one fit parameter, ΓM( Speed of side-feeding of electrons
from the metal band to the M shell )49

6. Summary

Summary & Outlook๏ Muonic atom is an ideal probe to explore QED under
extremely strong electric fields

๏ Introduced TES microcalorimeters๏ Successfully conducted muonic Ne X-ray measurementwith 0.1 atm gas target under an intense pulsed muon beam

๏Towards further measurements of higher atomic number Z(having a larger contribution of QED effect), a new TES
spectrometer having the energy range of < 50 keV and < 130
keV is developing.

๏ [Serendipity] fortunately observed dynamics of the muon
atom formation process for the first time51