a high energy resolution gamma-ray tes calorimeter with 0 ... · a high energy resolution gamma-ray...
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A high energy resolution gamma-ray TES calorimeter with 0.5 ms response time
T. Oshima, Y. Yamakawa, H. Kurabayashi, A. Hoshino,Y. Ishisaki, T. Ohashi,
(Department of Physics, Tokyo Metropolitan University )K. Misutda (ISAS/JAXA)
K. Tanaka (SII Nano-Technology)
Applications & requirements• Astrophysics
– 44Ti (68.9/78.3 keV, T1/2~ 59 yr) γ-ray emission from supernovaremnants
• direct information on the radioactive isotopes produced by the explosions• not obscured by galactic dust
⇒ provides a stringent test of theories of supernova nuclear reactions. Fly γ-ray calorimeters on balloons!• Material analysis (EDXRD)
– γ-ray diffraction spectroscopy of crystals under ultra highpressure(~MPa) → Poster by A. Hoshino
– interesting structures ~80keV– time evolution ⇒ fast response time
• Our GOAL–Bandwidth ~ 100 keV–Energy resolution ΔE ~ a few times 10 eV–Fast response time τ << 1ms–High Efficiency @ ~80keV
Ti/Au TES
Sn (Z=50)(t0.3mm)
Energy (keV)
Qua
ntum
effi
cien
cy
Our first trial (SII-115)
TES: Ti/Au(40/70nm)X-ray absorber:Au(500nm)Membrane: SiN bridgeTc: 151 mK
Pulse shape analysisshows no significantfluctuation of τrise .Let’s try a faster one!
500 µm
300 µm
SII-115
Si
Au
Sn absorber
a bSiN membraneNbTES
cross section
epoxy
ΔEFWHM =138 eV @60keVτrise~ 110µs
τfall ~ 2.0 ms
b
a15µm spacer
Sn
0.79mm0.87mm
Ca =11.2 pJ/K
ΔEbaseline= 81 eV
Energy(keV)
Cou
nts/
bin
Energy resolution:Response:
Trade off• Trade off between the signal loss and the position
dependence.– τfall↓( ≅ G↑) ⇒ τfall / τrise ↓ ⇒ ΔTTES ↓ ⇒ signal loss– τrise↓( = Ga ↑) ⇒ Position dependence in the absorber↑
• How fast can we make?⇒ SPICE simulation• Boundary conditions:
–Limited Ga : @150mK (@100mK)• Stycast 2850FT ~ 100nW/K (30nW/K) for r =100µm, h=20µm• Kapitza ~ 170nW/K (50nW/K) per r =100µm boundary (2 boundaries)• electron-phonon ~ 450nW/K (85nW/K)⇒ Ga ~ 50nW/K (~20nW/K)
–Saturation at the transition edge:• lower limit to Ca
Ca , Ta
Ga
C, T
Tb
G
Our Second trial (SII-155)
TES: Ti/Au(40/120nm)X-ray absorber: Au(500nm)Membrane: SiN squareTc: 151 mKC = 2.0 pJ/KG = 3.5 nW/KΔE = 12 eV @ 5.9 keV
500 µm
300 µm
SII-155
Au
( )
Saturation
approx.
Ca ~ 7pJ/K
⇒ size ~ 700µm
Temperature change of the TES
Ca (pJ/K)
ΔT
(mK)
10nW/K
20nW/K
50nW/K Ga =100nW/K
E =100keV, C =2pJ/K
Ca , Ta
Ga
C, T=153mK
3.5nW/KTb=132mK
Thermal model
G
60 keV
100 keV
T (mK)
R (m
Ω)
ΔTmax < 1mK
SPICE Simulation: Noise spectrumEquivalent circuit
Rs
RTES
LinC
Ca1/Ga
1/G
PETF
thermal electrical
Ca , Ta
Ga
C, T=153mK
3.5nW/KTb=132mK
Thermal model
G
Frequency (Hz)
Johnson noise of– Shunt resistor Rs =3mΩ– TES RTES = 25.58mΩPhonon noise at– G = 3.5nW/K– Ga = 10nW/K– Readout (SQUID) noise 20pA/√Hz– Total
Current noise spectrum
(LLNL: Miyazaki et al.)
I n (A
/Hz1
/2 )
SPICE Simulation: Position dependence (1)• FEM-like model with SPICE
– Absorber: 3D network of C and G 7 x 7 x 3 elements (Please imagine a 3D picture!)– stycast: 1 element– TES: 1 element
• generate pulses using a modeled R-T curve• optimal filtering with simulated noise spectrum⇒ pulse height ⇒ ΔEFWHM
• Material Parameters of Sn:– κSn = 1.24T 3.1 W/K/m (foil)– cSn = 0.054 pJ/K
• Scan parameters: Ga , absorber area α
T (K)
R (Ω
)
modeled R-T curve
Operatingpoint
Thermal model
stycast
TESG
Ga/2
Ga/2
SPICE Simulation: Position dependence (2)
Make Ga as large as possible! 700µm 25 eV && τfall = 300µs1050µm 36 eV && τfall = 600µs achievable.
Ga (nW/K)
ΔES/N (eV)
ΔEposition (eV)
τfall (ms)
ΔEtotal (eV)
size = 700µm, 1050µm
Our Second trial (SII-155)
Stycast 2850FT
300µm
TES: Ti/Au(40/120nm)X-ray absorber: Au(500nm)Membrane: SiN squareTc: 151 mKC = 2.0 pJ/KG = 3.5 nW/KΔE = 12 eV @ 5.9 keV
Ca = 6.9 pJ/K
500 µm
300 µm
SII-155
630 µm
670 µm
Sn
Surface roughness of Sn: σ ~ 2.5 µm σ ~ 0.6 µmPolished
with aluminapowder(~3 µm)
SII-155+Sn results (1)
good linearity2.1%@60keV
±10eV
Comparison withthe SPICE simulation
Measured 60keV Simulation: Ga=40nW/K 30nW/K 20nW/K 10nW/KΔ
I (µA
)
Time (ms)
Ga ~ 30nW/K
Time (ms)
ΔI (µA
)
averaged pulses of various EE=60keVτrise = 46 µsτfall = 520 µs
Operating point(Vb =1.25µV, α ~200)
60 keV
100 keV
T (mK)
R (m
Ω)
SII-155+Sn results (2)
Np-L
AmSn-escapeAm
Sn-escapeAm
Np-LβNp-Lα
Np-Lγ
241Am5367sec, 20580 events
ΔEbaseline=37.9±0.7 eV
SII-155+Sn results (2)
Np-L
AmSn-escapeAm
Sn-escapeAm
Np-LβNp-Lα
Np-Lγ
241Am5367sec, 20580 events
ΔEFWHM =38.4±0.9 eV@60 keV
ΔEbaseline=37.9±0.7 eV
Energy resolution of the nuclear γ-ray lines(26, 60 keV)agrees with ΔEbaseline⇒ no degradation by the position dependence
SPICE simulation: Ideal 100mK device
Ca (pJ/K)
ΔT
(mK)
10nW/K
20nW/K
50nW/K Ga=100nW/K
E=100keV, G=1nW/K
15.15.014.2970301140012.76.810.842040310509.73.59.1160405700
ΔEtot(eV)ΔEpos(eV)ΔES/N(eV)τfall (µs)Ga(nW/K)G(nW/K)Size(µm)
Results for E=60keV signalScan parameters: Ga = 10 - 50nW/K, G = 1 - 5nW/KHard to list all. Results for some parameters are shown.
Ca ~ 4pJ/K⇒ size ~ 1000µm
Saturation:
α
model R-T curve
T (K)
R (Ω
)
2mK
T = 98.7mK R = 0.3 Ω α ~ 50
Summary• Designed a fast response γ-ray TES calorimeterusing SPICE simulation.
• 150mK device with 700µm x 700µm x 300µm tinabsorber demonstrated
– τfall = 520 µs, τrise = 46µs– ΔE= 38.4±0.9 eV eV@60keV, ΔEbaseline=37.9±0.7 eV– No degradation of ΔE due to the position dependence
seen as the simulation tells.• SPICE simulation for 100mK device shows
– τfall < 500 µs– ΔE < 15 eVis achievable with 1mm2 x 300um absorber
SPICE Simulation: non-linearityα
T (K)
R (Ω
)
modeled R-T curve
Operatingpoint
・Generate simulated pulses using a modeled R-T curve・Apply optimal filtering⇒ pulse height
Equivalent circuit
Rs =3mΩRTES
LinC
Ca1/Ga
1/G
ETF
thermal electrical
Ca , Ta
Ga
C, T=153mK
3.5nW/KTb=132mK
Thermal model
G
Ga (nW/K)
non-
linea
rity
(%) size=500µm (3.8pJ/K)
750µm (8.6pJ/K) 1000µm (15pJ/K) 1250µm (24pJ/K) 1500µm (34pJ/K)