COBANDᐇ㦂䛻䛚䛡䜛Hf-STJ㛤Ⓨ
CiRfSE ⣲⢏Ꮚᵓ㐀㒊㛛Ṋᨻ ೺୍

CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

1COBANDᐇ㦂x COBANDᐇ㦂ᴫせx Ᏹᐂ㉥እ⥺⫼ᬒ㍽ᑕ䛾䜶䝛䝹䜼䞊ศᕸ䜢 ᐃ䛧䚸䛭䛾୰䛛䜙Ᏹᐂ⫼ᬒ䝙䝳䞊䝖䝸䝜ᔂቯ஦㇟䜢᥈䛩䚹x Ᏹᐂ⫼ᬒ䝙䝳䞊䝖䝸䝜䛾Ⓨぢx 䝙䝳䞊䝖䝸䝜㉁㔞䛾Ỵᐃ or ᑑ࿨䛾ୗ㝈್᭦᪂x ⾨ᫍᐇ㦂x ேᕤ⾨ᫍ䛻䛶100᪥㛫䛾䝕䞊䝍཰㞟(2020ᖺ௨㝆)x W(Q3) ~ 1017ᖺ䛾ឤᗘx ᮃ㐲㙾: ┤ᚄ20cm, ど㔝: 0.1㼻
x ᳨ฟჾ: Hf-STJ (Eγ ~25meV䜢ศゎ⬟2%௨ୗ䛷 ᐃ䛷䛝䜛ᚲせ䛜䛒䜛)CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

2

Superconducting Tunnel Junction (STJ)x ㉸ఏᑟయ䜢⏝䛔䛯ග᳨ฟჾx 䜻䝱䝸䜰⏕ᡂ䛻ᚲせ䛺䜶䝛䝹䜼䞊䛜ᑠ䛥䛔䛯䜑䚸䜶䝛䝹䜼䞊ศゎ⬟䛻ඃ䜜䜛x ᵓ㐀x ㉸ఏᑟయ/⤯⦕⭷(䝖䞁䝛䝹䝞䝸䜰)/㉸ఏᑟయ䛸䛔䛖ᵓ㐀䛾䝆䝵䝉䝣䝋䞁⣲Ꮚx ኱䛝䛥䠖 ⦪ᶓ ᩘ10䡚ᩘ100μmゅ 㽢 㧗䛥 ᩘ100nmx ⤯⦕⭷䛿ཌ䛥ᩘnm⛬ᗘ

Hf3

䛣䛾㡿ᇦ䜢౑⏝䛩䜛

STJ䛾IV≉ᛶ䞉ືసཎ⌮ືస᫬䛻䛿䚸䞉⤯⦕⭷䛻ᖹ⾜䛻☢ሙ䜢䛛䛡䚸䝆䝵䝉䝣䝋䞁㟁ὶ䜢ᢚไ䛩䜛䞉⇕ບ㉳䛻䜘䜛₃䜜㟁ὶ䜢ᢚไ䛩䜛䛯䜑,Tc/10⛬ᗘ䜎䛷෭༷䛩䜛䞉ୖୗ㟁ᴟ䛻0<V<2Δ䛾㟁ᅽ䜢䛛䛡䜛

RdRn㟷䠖ගධᑕ᫬ᶳ䠖ග䛺䛧ග᳨ฟჾ䛸䛧䛶䛾ືసཎ⌮ ග䛜ධᑕ䛧䚸 ㉸ఏᑟయ୰䛷ග㟁ຠᯝ䛷྾཰䛥䜜䜛 䜽䞊䝟䞊ᑐ䛾஋㞳䜔䝣䜷䝜䞁⏕ᡂ䛜㉳䛣䜚䚸ධᑕග䛾䜶䝛䝹䜼䞊䛻ᑐᛂ䛧䛯ᩘ䛾‽⢏Ꮚ䛜ບ㉳䛥䜜䜛䚹 ບ㉳䛥䜜䛯‽⢏Ꮚ䛜䝖䞁䝛䝹䛧䛶䜒䛖୍᪉䛾㉸ఏᑟయ䜈⛣ື䛧㟁ὶ䛸䛧䛶ほ 䛥䜜䜛䚹Æ 㟁ὶ䜢 䜛䛣䛸䛷ධᑕග䛾䜶䝛䝹䜼䞊䜢 ᐃ䛷䛝䜛Δ䠖㉸㟁ᑟయ䛾䜶䝛䝹䜼䞊䝞䞁䝗䜼䝱䝑䝥4

Hf-STJ䛾䜶䝛䝹䜼䞊ศゎ⬟˂ኅኪወኋዙክዐኦኋዀአኴ)ኲቾካ⥯⷟(⏴⺓⏘⷟ቑኅኪወኋዙ
7F怔↬⺝慱䲊䂸ㄵ STJ䛾䜶䝛䝹䜼䞊ศゎ⬟ߪா ൌͳǤ͹ȟ ‫ܧܨ‬ Δ䛜ᑠ䛥䛔䜋䛹‽⢏Ꮚ䛾⏕ᡂᩘ䛜኱䛝䛟䛺䜚䚸䜶䝛䝹䜼䞊ศゎ⬟䛜Ⰻ䛔䚹
Expected energy resolution of Hf-STJ

MaterialTc(K)'(meV)

Si䠉

1200

Niobium

9.20

1.550

Aluminum

1.14

0.172

Hafnium

0.16

0.021

 Nq.p. = 25meV/1.7' =700 (Nb䛾ሙྜ䛿9ಶ)

25meV

 䝣䜯䝜ᅉᏊ䛻Nb䛸ྠ䛨0.2䜢௬ᐃ䛩䜛䛸2%䛾䜶䝛䝹䜼䞊ศゎ⬟䜢㐩ᡂ䛷䛝䜛䚹
 ₃䜜㟁ὶ䜈䛾せồ್: Rd > 2MΩ (ಙྕᖜ1μs䛾ሙྜ)

Energy[eV] 1

Expected photon energy of neutrino decay5

䛺䛬Hf䛺䛾䛛x ' < 0.29meV䛾㉸ఏᑟయ䛷䛒䜜䜀䚸䜶䝛䝹䜼䞊ศゎ⬟䛾せồ䛿‶䛯䛩x ߪா ൌͳǤ͹ȟ ‫ܨ‬ɂx STJ䛿⇕䝜䜲䝈䜢ᢚไ䛩䜛䛯䜑䚸㉸ఏᑟ㌿⛣ᗘ䛾1/10௨ୗ䛻෭༷䛩䜛Æ Tc䛾኱䛝䛔䜒䛾䛜ྲྀ䜚ᢅ䛔䛧䜔䛩䛔䚹䛯䛰䛧䚸2Δ = 3.5kBTc (BSC theory) 䚹MaterialNbPb
TaSnAlTi
HfIrBeWRh

Tc[K]
9.29
7.2
4.48
3.7
1.18
0.39
0.165
0.099
0.023
0.016
0.002

Δ[meV]
1.55
1.365
0.7
0.575
0.172
0.058
0.021
0.014
0.00340.00250.0003

Hf䛿Δ䛾せồ䜢‶䛯䛧䛴䛴䚸㧗䛔Tc䜢ᣢ䛳䛶䛔䜛䚹
䜎䛯䚸HfOx䛜STJ䛾⤯⦕⭷䛸䛧䛶⏝䛔䜙䜜䛯ᐇ⦼䛜䛒䜛䚹

ÅNb/HfOx-Hf/Nb STJ䛾IV≉ᛶ(200Pmゅ)
Nb/HfOx/Hf/Nb = 200nm/?/3nm/200nm

High-quality Nb/HfOx-Hf/Nb Josephson junction,Appl.Phys. Lett, Vol.60, No.24, 15 June 1992, S.Morohashi et.al.Hf-STJ䛾సᡂ䞉ホ౯⎔ቃx 㧗䜶䝛䝹䜼䞊ຍ㏿ჾ◊✲ᶵᵓ(KEK)䛾䜽䝸䞊䞁䝹䞊䝮䛻䛶సᡂx 䝬䜾䝛䝖䝻䞁䝇䝟䝑䝍䛻䜘䜛Hfⷧ⭷ᙧᡂx 䝣䜷䝖䝸䝋䜾䝷䝣䜱䛸䝗䝷䜲䜶䝑䝏䞁䜾䛻䜘䜛ᚤ⣽ຍᕤx 㓟⣲㞺ᅖẼ୰䛷䛾㓟໬䛻䜘䜛⤯⦕⭷ᙧᡂx ᕼ㔘෭෾ᶵ@⟃Ἴ኱Ꮫ䛻䛶෭༷ヨ㦂䜢ᐇ᪋x 120mK⛬ᗘ䛻෭༷䛧䚸ᅄ➃Ꮚἲ䛷⣲Ꮚ䛾IV≉ᛶ䞉ගᛂ⟅ホ౯䜢⾜䛳䛶䛔䜛䚹
ᕪື䜰䞁䝥

7HfOx

ᚑ᮶䛾Hf-STJ⣲Ꮚ

TEMほᐹ⤖ᯝ
HfHfSiᇶᯈx Pure Hf⣲Ꮚ䠖Hf䛾䜏䛷〇స䛧䛯䝃䞁䝥䝹(100μmゅ)

HfOx~1.5nmHfx Hf/HfOx/Hf = 250nm/ 1.5nm(⇕㓟໬30Torr,1H)/300nm

x ⤯⦕⭷(HfOx)䛜1.5nm⛬ᗘ䛷䛝䛶䛔䜛䛜䚸₃䜜㟁ὶ䛜኱䛝䛔x ⤯⦕⭷䛻Ḟ㝗䛜䛒䜛䛸⪃䛘䜙䜜䜛䛯䜑䚸HfOx䛾ရ㉁ᨵၿ䛜ᚲせ30Torr,1H㓟໬
100μm㽢100μm
T= 50䡚60mK☢ሙ༳ຍ䛺䛧ᚑ᮶䛾Hf-STJ⣲Ꮚ䛾₃䜜㟁ὶ ᗘ౫Ꮡᛶᕥᅗ䛾ᣑ኱⇕ບ㉳䛾⌮ㄽᘧ䛛䜙኱䛝䛟እ䜜䛶䛔䜛

88ⷧ䛔Alᒙ䜢㏣ຍ䛧䛯䝃䞁䝥䝹• ₃䜜㟁ὶ䛾ᢚไ䛾䛯䜑䚸ᵓ㐀䜢ぢ┤䛧⤯⦕⭷䛸ୖ㒊Hfᒙ䛾㛫䛻Alᒙ䜢㏣ຍ• 䝷䞁䝥䜶䝑䝆ᆺ䝆䝵䝉䝣䝋䞁᥋ྜ⣲Ꮚཬ䜃䛭䛾〇㐀᪉ἲ• ≉㛤2003-069094 (P2003-69094A)• ୖୗ䛷␗䛺䜛㉸ఏᑟయ䜢⏝䛔䜛䛣䛸䛷₃䜜㟁ὶ䛜ῶ䜛• 䛣䜜䜢ཧ⪃䛻…
• 䛯䛰䛧䚸సᡂ⿦⨨䛾㒔ྜୖAl䛛Nb䛧䛛౑䛘䛺䛔• Al/Nb䜢ཌ䛟✚䜐䛸Hf䛾Δ䛻ᙳ㡪䛜䛷䜛䚹• Æ ⤯⦕⭷┤ୖ䛻ⷧ䛟Al/Nb䜢ᡂ⭷䛩䜛䚹Structure of ramp-edge Josephson junctionⷧ䛔Alᒙ䜢㏣ຍ䛧䛯䝃䞁䝥䝹x ₃䜜㟁ὶ䛾ᢚไ䛾䛯䜑䚸ᵓ㐀䜢ぢ┤䛧⤯⦕⭷䛸ୖ㒊Hfᒙ䛾㛫䛻Alᒙ䜢㏣ຍ(10nm)
 䝆䝵䝉䝣䝋䞁㟁ὶ䜢ほ䚹☢ሙ䛷ᢚไ䛥䜜䜛䛣䛸䜢☜ㄆ䚹

 Δ = 20~25μeV (~ΔHf) Ileak @20μeV = 5μA@128mK (200μmゅ) ₃䜜㟁ὶ䛜Hf䛾䜏䛷సᡂ䛧䛯䝃䞁䝥䝹䛸ẚ㍑䛧䛶1/4䛻ῶᑡ䚹(䝃䜲䝈ᕪ䜢⪃៖䛻ධ䜜䜜䜀1/16)
 ᨵၿ䛿䛧䛯䛜䚸䛔䜎䛰䛻せồ್䛿㐩ᡂ䛧䛶䛔䛺䛔䚹(せồIleak 䠜20μeV = 30pA@120mK)

200μm㽢200μm
Hf-STJ
2μA/div2μA/div

10μV/div

10μV/div

T = 128mK
B = 0 Gauss

T = 128mK
B = 5 Gauss

10μA/div

20μV/div☢ሙ༳ຍ(5 Gauss)

10μA/div

20μV/div

10Alᒙ䜢㏣ຍ䛧䛯Hf-STJ ගᛂ⟅ヨ㦂䝟䝹䝇ග䛻ᑐ䛩䜛ᛂ⟅ Ἴ㛗465nm laser 100msẖ䛻5μs㛫5MHz(25ᅇ)䛾Ⓨ᣺
Differential amp.
Attenuator

Power supply
Refrigerator
Light fiber

Laser
11ᐇ㦂䛻⏝䛔䜛䛻䛿₃䜜㟁ὶ䛜኱䛝䛩䛞䜛䛜䚸ග᳨ฟჾ䛸䛧䛶䛾ືస䛧䛶䛔䜛䚹ග᳨ฟჾ䛸䛧䛶ືస䛩䜛䝃䞁䝥䝹䜢సᡂ䛷䛝䛯䛜䚸₃䜜㟁ὶ䛜኱䛝䛟ᨵၿ䛜ᚲせ䚹Alᒙ䜢㏣ຍ䛧䛯Hf-STJ䛾₃䜜㟁ὶ

₃䜜㟁ὶ䛾ཎᅉ䛸䛧䛶⪃䛘䜙䜜䜛䛣䛸x ⇕ບ㉳
xIleak(thermal) ҃√ࢀ ࢋ(−ࢤ/࢑࢈ࢀ)ᗘ౫ᏑᛶIleak(thermal) ҃√ࢀ ࢋ(−ࢤ/࢑࢈ࢀ)Leakage current ofHf-STJ w/ Al layerx ⤯⦕⭷䛾Ḟ㝗x 㓟໬䛜୙༑ศx 㓟໬⭷䛜୙ᆒ୍x సᡂ䞉ホ౯䛾ᕤ⛬䛷㈇Ⲵ䛜᥃䛛䜚◚ᦆ• Alᒙ䜢㏣ຍ䛧䛯Hf-STJ䛾₃䜜㟁ὶ䛾⌮ㄽᘧ䛛䜙䛪䜜䛶䛔䜛䚹• Æ ᵓ㐀ⓗ䛺ၥ㢟䛜␲䜟䛧䛔䚹ᗘ౫Ꮡᛶ䛿䚸⇕ບ㉳䛻䜘䜛₃䜜㟁ὶ䛾㓟໬୙㊊x ⌧ᅾ䛾㓟໬᮲௳(⇕㓟໬᮲௳30Torr, 1H)䛿䚸Hf㓟໬⭷䛾సᡂ஦౛䛸ẚ㍑䛧䛶༑ศᙉ䛔x Ex. 30Pa (=0.23Torr), 30min, Nb/HfOx-Hf/Nb-STJx 䛣䜜䜎䛷䛸␗䛺䜛㓟໬⭷䛾సᡂ᪉ἲ䜢ヨ䛧䛶䜏䜛䚹x 䝥䝷䝈䝬㓟໬x 㓟⣲䜢䝥䝷䝈䝬໬䛧䛶Hf⾲㠃䛻䜆䛴䛡䜛䚹x ⇕㓟໬䛛䜙䝥䝷䝈䝬㓟໬䛻䛩䜛䛣䛸䛷䝆䝵䝉䝣䝋䞁⣲Ꮚ䛾₃䜜㟁ὶ䛜ᢚไ䛥䜜䛯ሗ࿌䛒䜚䚹x 䛣䜜䜎䛷⿦⨨䛾ᨾ㞀䛷ヨ䛫䛺䛛䛳䛯䛜䚸ಟ⌮䛥䜜䛯䛾䛷㏆᪥୰䛻䝔䝇䝖䛩䜛ணᐃ䚹13

CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

Hf⾲㠃⢒䛥
x Hf-STJ䛾᩿㠃ほᐹ䜢⾜䛳䛯䛸䛣䜝䚸ୗ㒊Hf䛾พฝ䛜㠀ᖖ䛻኱䛝䛟䛺䛳䛶䛔䛯䚹x 㓟໬⭷䛜୙ᆒ୍䛻䛺䜛ྍ⬟ᛶx సᡂ㐣⛬䛷ᒁᡤⓗ䛻㈇Ⲵ䛜䛛䛛䜛ྍ⬟ᛶᣑ኱
HfAl(white curve)
HfOx
HfHf-STJ w/ Al layer䛾᩿㠃ᅗ

x Hfⷧ⭷䛾ᖹᆠ໬x ᡂ⭷᮲௳䜢ኚ᭦䛩䜛䛣䛸䛷ᖹᆠ䛺⭷䛾సᡂ䛿ྍ⬟䚹x 䛯䛰䛧䚸ෆ㒊ᛂຊ䛜ᙉ䛟䛺䜛ഴྥ䛜䛒䜚ᛂຊ㛤ᨺ䛻䜘䜛⤯⦕⭷䛾◚ᦆ䛜㉳䛣䜚䜔䛩䛟䛺䜛䚹x ᛂຊ䛜ᙅ䛟⾲㠃䛜⢒䛔ⷧ⭷䜢ᙧᡂ䛧䛶䚸⾲㠃䜢䜲䜸䞁⾪✺䛷ᖹᆠ໬䛩䜛䛣䛸䛷䚸ᛂຊ䛸⁥䜙䛛䛥䜢୧❧䛩䜛᪉ἲ䜢䝔䝇䝖୰䚹ᖹᆠ໬๓ᖹᆠ໬ᚋ(䜲䜸䞁⾪✺)ᑠᆺ໬x ⣲Ꮚ䛾ᑠᆺ໬䛻䜘䜛₃䜜㟁ὶ䛾ᢚไ䜒ᐇ᪋ணᐃ䚹x ⌧ᅾホ౯䛧䛶䛔䜛⣲Ꮚ䛿200μmゅ䚹
x 10μmゅ䛻䛩䜛䛣䛸䛷1/400䛻䛺䜛䛣䛸䛜ᮇᚅ䛥䜜䜛䚹

Hf-STJ w/ Al layer
measuredᑠᆺ໬:
200μm㽢200μm Æ10μm㽢10μm
expected⤯⦕⭷䛾ᨵၿ䛷2᱆䛾ᨵၿ䛜ᚲせRequired Ileak

Pure Hf⣲Ꮚ䛾₃䜜㟁ὶ䝃䜲䝈౫Ꮡᛶ

Goal: 10pA@50mK㓟໬᮲௳

200μm㽢200μm

100μm㽢100μm

50μm㽢50μm

20Torr, 1H

87μA

42μA

䠉

30Torr, 1H

100μA

24μA

5μA

CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

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䜎䛸䜑
x COBAND⾨ᫍᐇ㦂䛻౑⏝䛩䜛᳨ฟჾ䛸䛧䛶Hf-STJ䛾㛤Ⓨ䜢⾜䛳䛶䛔䜛䚹x Hf-STJ䛻Alᒙ䜢㏣ຍ䛩䜛䛣䛸䛷₃䜜㟁ὶ䜢ᚑ᮶䛾⣲Ꮚ䛾1/4䛻ᢚไ䛩䜛䛣䛸䛻ᡂຌ䚹x Alᒙ䜢㏣ຍ䛧䛯Hf-STJ⣲Ꮚ䛷ྍどගᛂ⟅䜢☜ㄆ䚹x ග᳨ฟჾ䛸䛧䛶ືస䛩䜛Hf-STJ䜢సᡂ䛷䛝䛯䛜䚸₃䜜㟁ὶ䛿せồ್䜘䜚㠀ᖖ䛻኱䛝䛔䚹x 䝥䝷䝈䝬㓟໬䛻䜘䜛⤯⦕⭷䛾సᡂ䚸ⷧ⭷⾲㠃䛾ᖹᆠ໬䛺䛹䛻䜘䜛₃䜜㟁ὶ䛾ᨵၿ䜢ヨ⾜୰䚹CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

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CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

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CiRfSE䝽䞊䜽䝅䝵䝑䝥20170124

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㝧ᴟ㓟໬

HfOx

Anode oxidation

ⷧ䛔Alᒙ䜢㏣ຍ䛧䛯䝃䞁䝥䝹1x ₃䜜㟁ὶ䛾ᢚไ䛾䛯䜑䚸ᵓ㐀䜢ぢ┤䛧⤯⦕⭷䛸ୖ㒊Hfᒙ䛾㛫䛻Alᒙ䜢㏣ຍ(10nm)
 Ileak@20μeV = 60nA@140mK (200μmゅ) 䝆䝵䝉䝣䝋䞁㟁ὶ䛜ほ䛷䛝䛺䛔 Δ = 30~100μeV. Å Al䛾㏆᥋ຠᯝ

 ₃䜜㟁ὶ䛿ᨵၿ䛥䜜䛯䛜…
 ಙྕ䜒㏻䛧䛻䛟䛔 Δ䛜኱䛝䛟䛺䛳䛶䛔䜛 Æ 䜶䝛䝹䜼䞊ศゎ⬟䛾ᝏ໬ගᛂ⟅
λ=465um
10MHz oscillation 260μs per 1s
Laser trigger

T=140mK
B = 0Gauss

STJ current

STJvoltage

Too late20