173

˙ ‫঺ڀݚ‬հ

FASER ࣮‫ݧ‬ͷ‫ݐ‬ઃ։࢝ͱࠓ‫ޙ‬ͷల๬‫۝‬भେֶઌ୺ૉཻࢠ෺ཧ‫ڀݚ‬ηϯλʔ

KEK ૉཻࢠ‫ॴڀݚ֩ࢠݪ‬Ի໺ ӯढ़
otono@phys.kyushu-u.ac.jpా‫ ۼ‬༸հ
yosuke.takubo@kek.jp

2019 ೥ (ྩ࿨‫ݩ‬೥) 11 ݄ 15 ೔1͸͡Ίʹ
MeV ͔Β GeV ఔ౓ͷ͍࣭ܰྔΛ࣋ͪ, ૉཻࢠͷඪ४໛‫ͱࢠཻܕ‬ඇৗʹऑ͘૬‫͢༻࡞ޓ‬Δ৽ཻࢠ͸, ඪ४໛‫ܕ‬

SWIMPs(Super WIMPs)[5] ͳͲ, ҉ࠇ෺࣭ີ౓ͷ‫؍‬ଌ஋Λ࠶‫͖Ͱݱ‬Δ෺ཧϞσϧ͸ଘࡏ͢Δɻ͔͠͠, ຊߘͰ͸ WIMP ͳ͠ϛϥΫϧʹ‫͍ͯͮج‬࿩ΛਐΊΔɻΛ௒͑Δ৽෺ཧͷީิͱͯ͠, ۙ೥ੈքతʹ஫໨ΛूΊ

WIMP ͳ͠ϛϥΫϧͷଞͷ෺ཧతҙٛͱͯ͠, ʮCoreCusp ໰୊ʯΛղܾͰ͖Δͱ͍͏΋ͷ͕͋Δ [6]ɻӉ஦‫؍‬͍ͯΔ [1]ɻFASER(ForwArd Search ExpeRiment) ࣮‫ݧ‬ଌʹΑͬͯ, ۜՏͷ಺ଆͱ֎ଆͷճస଎౓͕Ұఆ͍ͯ͠[2, 3] ͸, CERN ʹઃஔ͞Ε͍ͯΔ LHC(Large Hadron
Collider) Ճ଎‫ث‬Λ༻͍ͨ ATLAS ࣮‫ݧ‬ͷϏʔϜিಥ఺

Δ͜ͱ͕෼͔͍ͬͯΔ͕, ͦΕΛ࣮‫͢ݱ‬ΔͨΊʹ͸ۜՏ͔Β 480 m Լྲྀʹଌఆ‫ث‬Λઃஔ͠, ͍ܰ৽ཻࢠΛ୳ࡧதͷ҉ࠇ෺࣭ͷີ౓͸Ұ༷Ͱͳ͚Ε͹ͳΒͳ͍ɻ͔͠͠,WIMPs Λ҉ࠇ෺࣭ͱԾఆ͢Δͱ, ҉ࠇ෺࣭ͷີ౓͸ۜ͢ΔϓϩδΣΫτͰ͋ΔɻLHC ͸ 2018 ೥ 12 ݄͔Β௕Տத৺ʹϐʔΫΛ࣋ͭΑ͏ͳ෼෍ʹͳΓ, ‫؍‬ଌࣄ࣮ͱ߹

‫ظ‬γϟοτμ΢ϯʹೖ͍ͬͯΔ͕, 2021 ೥ʹ࠶Քಇ͢Δ

Θͳ͍ɻ͜ΕΛ Core-Cusp ໰୊ͱ͍͏ɻ҉ࠇ෺࣭ؒͷ͜ͱʹͳ͍ͬͯΔ (Run3)ɻFASER ࣮‫ݧ‬͸ Run3 ౰ॳͷ૬‫͕͋༻࡞ޓ‬Ε͹, Core-Cusp ໰୊͕ղܾͰ͖Δ͜ͱ͕࣮‫ݧ‬։࢝Λ໨ࢦ͓ͯ͠Γ, ‫ࡏݱ‬, ‫ݕ‬ग़‫ث‬ͷ։ൃ͕‫ٸ‬ϐο෼͔͓ͬͯΓ, WIMP ͳ͠ϛϥΫϧͷΑ͏ʹ҉ࠇ෺࣭ؒνͰਐΜͰ͍ΔɻຊߘͰ͸, ͍ܰ৽ཻࢠ୳ࡧͷҙٛͱ,ͷ૬‫༻࡞ޓ‬Λഔհ͢Δ৽ཻࢠ͕͋Ε͹, ͦͷΑ͏ͳঢ়ଶFASER ࣮‫ݧ‬ͷ४උঢ়‫঺͍ͯͭʹگ‬հ͢ΔɻΛ࣮‫͖Ͱݱ‬Δ (ਤ 1 ӈ)ɻ

WIMP ͳ͠ϛϥΫϧΛ࣮‫͖Ͱݱ‬Δ৽ཻࢠʹ͸͍ͭ͘

2͍ܰ৽ཻࢠ୳ࡧͷҙٛऑ͍૬‫༻࡞ޓ‬ఔ౓ͷ‫Ͱ͞ڧ‬ඪ४໛‫ͱࢠཻܕ‬૬‫༻࡞ޓ‬͠, O(100 GeV) ͷ࣭ྔΛ࣋ͭ҉ࠇ෺ཻ࣭ࢠΛ WIMPs(Weakly Interacting Massive Particles) ͱ‫Ϳݺ‬ɻ΋͠,҉ࠇ෺࣭͕ WIMPs Ͱ͋Ε͹, Ӊ஦‫؍‬ଌͰಘΒΕͨ҉ࠇ෺࣭ີ౓Λͦͷ೤࢒ଘྔͰ্ख͘࠶‫͖Ͱݱ‬Δ (ʮWIMP
ϛϥΫϧʯͱ‫ݺ‬͹ΕΔ)ɻ
Ұํ, ҉ࠇ෺࣭ͷ࣭ྔ͕ O(100 GeV) ҎԼͰ΋, MeV

͔Β GeV ఔ౓ͷ͍ܰ৽ཻࢠ͕҉ࠇ෺࣭ͷഔհཻࢠͱ͠
ͯଘࡏ͠, γ ͳͲͷඪ४໛‫߹ࠞͱࢠཻܕ‬ύϥϝʔλ (�) Ͱऑࠞ͘͡Γ߹͍ͬͯΕ͹ (ਤ 1 ࠨ), ‫؍‬ଌ͞Ε͍ͯΔ҉ࠇ෺࣭ີ౓Λ࡞Γग़͢͜ͱ͕Ͱ͖Δ (ʮWIMP ͳ͠ϛϥΫϧʯͱ‫ݺ‬͹ΕΔ)ɻ͞Βʹ, ৽ཻࢠͷ࣭ྔ͕ O(eV) ఔ౓ʹܰ͘, � ͕ඇৗʹখ͚͞Ε͹௕ण໋ͱͳΓ, ͜ͷ৽ཻࢠࣗମ͕҉ࠇ෺࣭ͷީิͱͳΓಘΔɻͱ͸͍͑, FASER ࣮‫ݧ‬͸ͦͷΑ͏ͳ৽ཻࢠʹ‫౓ײ‬Λ࣋ͨͳ͍ͷͰ, ͜͜Ͱ͸҉ࠇ෺࣭ͱඪ४໛‫ࢠཻܕ‬ͷ૬‫༻࡞ޓ‬Λഔհ͢Δ৽ཻࢠͷΈΛ୳ࡧର৅ͱ͢Δɻͳ͓, WIMP ͳ͠ϛϥΫϧҎ֎ʹ΋, SIMP(Strongly Interacting Massive Particle)[4] ΍͔ͷީิ͕͋Δɻ·ͣ, FASER ࣮‫ݧ‬ͷϕϯνϚʔΫ୳ࡧʹͳ͍ͬͯΔͷ͸, ৽ͨͳ U(1) ήʔδରশੑΛಋೖ
͢Δ͜ͱʹΑͬͯ༧‫͞ݴ‬ΕΔ҉ࠇϑΥτϯͰ͋Δ [7]ɻ҉ࠇϑΥτϯ͸ γ ͱࠞ߹͢Δ͜ͱʹΑͬͯ, ඪ४໛‫ࢠཻܕ‬ʹ่յ͢Δ͜ͱ͕Ͱ͖Δ (ਤ 1 ࠨ)ɻ
҉ࠇϑΥτϯҎ֎ͷ৽ཻࢠͷީิͱͯ͠͸, ରশੑͷഁΕʹ൐͏ٖೆ෦ɾΰʔϧυετʔϯϘιϯͰ͋Δ

ALP(Axion Like Particle)[8] ΍, ҉ࠇώοάε [9] ͳͲ͕͋Δɻͦͷଞ, FASER ࣮‫Ͱݧ‬͸εςϥΠϧɾχϡʔτϦϊͷΑ͏ͳதੑϨϓτϯ [10] ͷ୳ࡧ΋໨ࢦ͍ͯ͠Δɻ

LHC Λ༻͍࣮ͨ‫Ͱݧ‬͸, WIMP ϛϥΫϧΛԾఆͨ͠ॏ͍৽ཻࢠͷ୳ࡧΛߦ͖͕ͬͯͨ, ͜Ε·Ͱʹ͍͔ͳΔ
ஹީ΋‫͍ͳ͍͔ͯͬͭݟ‬ɻҰํ, WIMP ͳ͠ϛϥΫϧʹ
‫Ͱࡧ୳ࢠཻ৽͍ܰͮ͘ج‬͸, ੜ੒൓ԠͰ͋Δཅࢠɾཅࢠ
ඇ஄ੑࢄཚͷஅ໘ੵ͕ Bjorken εέʔϦϯάʹै͏ͨΊ, ௒લํͷཻࢠΛัΒ͑Δඞཁ͕͋ΔɻͦͷΑ͏ͳཻࢠ͸‫ݱ‬ঢ়ͷ LHC ࣮‫Ͱݧ‬͸୳ࡧͰ͖ͳ͍ɻLHC ͷߴ͍ੜ੒அ໘ੵΛ৽ཻࢠ୳ࡧʹ‫͢༻׆‬ΔͨΊʹ͸, ͜Ε͔Β঺հ͢Δ FASER ࣮‫͕ݧ‬།ҰͷղܾࡦͱͳΔɻ

274

ਤ 2: FASER ‫ݕ‬ग़‫ ͱث‬ATLAS ࣮‫ݧ‬ͷϏʔϜিಥ఺ͷҐஔؔ܎ʢ্ʣͱ, FASER ࣮‫ࠇ҉Ͱݧ‬ϑΥτϯΛัΒਤ 1: ͍ܰ৽ཻࢠ (A ) ͕, ҉ࠇ෺࣭ͱඪ४໛‫( ࢠཻܕ‬SM)

͑Δ֓೦ਤʢԼʣɻਤதͷ SCT ͸ඈ੻‫ݕ‬ग़‫ث‬Λදͯ͠ͱͷ૬‫༻࡞ޓ‬Λ γ ͱͷࠞ߹Λհ࣮ͯ͠‫͢ݱ‬Δ৔߹ʢࠨʣ͍Δɻ�ͱ, ҉ࠇ෺࣭ (χ) ͷ૬‫༻࡞ޓ‬Λഔհ͢Δ৔߹ʢӈʣͷϑΝΠϯϚϯɾμΠΞάϥϜɻ� ͸ A� ͱ γ ͷࠞ߹ͷ౓߹͍Λද͢ɻग़‫ʹث‬Αͬͯ, FASER ‫ݕ‬ग़‫͔ྲ্ྀث‬Β΍ͬͯ͘Δඪ४໛‫ࢠཻܕ‬Λ veto ͢ΔɻͦΕҎ֎ͷγϯνϨʔγϣϯ‫ݕ‬ग़‫ث‬͸ΧϩϦϝʔλͷ৘ใͱ߹ΘͤͯτϦΨʔൃߦʹ࢖

3

FASER ࣮‫ݧ‬

3.1

FASER ‫ݕ‬ग़‫ث‬༻͢Δɻ

FASER ࣮‫ݧ‬ͷίϯηϓτ͸, ʮ҆͘ʯʮૣ͘ʯʮ༏Εͨ୳ࡧ‫౓ײ‬ʯΛ࣮‫͢ݱ‬Δ͜ͱͰ͋Δɻ·ͣ, ʮ҆͘ʯͱʮૣ͘ʯʹ͍ͭͯ͸, FASER ࣮‫Ͱݧ‬͸, ௒લํํ޲ʹί

ਤ 2 ʹ FASER ‫ݕ‬ग़‫ ͱث‬ATLAS ࣮‫ݧ‬ͷϏʔϜিಥϦϝʔτ͞Εͯ΍ͬͯ͘Δ৽ཻࢠΛัΒ͑Δ͜ͱʹΑͬ఺ͷҐஔؔ܎Λࣔ͢ɻFASER ‫ݕ‬ग़‫ث‬͸, ATLAS ࣮‫ݧ‬ͯ, ‫ݕ‬ग़‫ث‬αΠζΛίϯύΫτʹͰ͖Δɻ͞Βʹ, ඈ੻ͷϏʔϜিಥ఺͔Β 480 m ཭Εͨ TI12 ͱ͍͏৔ॴʹ‫ݕ‬ग़‫ʹث‬͸ ATLAS-SCT ͷγϦίϯɾετϦοϓ‫ݕ‬ग़ઃஔ͞ΕΔɻ͜ͷ৔ॴ͸, LHC ͱ SPS(Super Proton‫ث‬Λ, ΧϩϦϝʔλʹ͸ LHCb ͷεϖΞɾϞδϡʔϧΛ

Synchrotoron) ͷ઀ଓτϯωϧͰ, LHC ͷલ਎Ͱ͋Δ

࢖༻͢Δɻ͜ΕʹΑΓ, ‫ݐ‬ઃίετ͸໿ 1 ԯԁʹԡ͑͞

LEP(Large Electron Positron collider) ͷ࣌୅ʹϏʔϜΒΕΔɻ͞Βʹ, ‫ʹط‬ੑೳ͕อূ͞Ε͍ͯΔ‫ݕ‬ग़‫ث‬Λ࢖ೖࣹʹ࢖༻͞Ε͍ͯͨɻLHC ͸৽ͨʹೖࣹ༻τϯωϧ

༻͢Δ͜ͱʹΑΓ, R&D ʹֻ͔Δ࣌ؒΛେ෯ʹ୹ॖͰΛ࡞ͬͨͨΊ, ‫ ࡏݱ‬TI12 ͸࢖ΘΕ͍ͯͳ͍ɻ͍ܰ৽ཻ͖, ૣ‫ݧ࣮ʹظ‬Λ࣮‫͖Ͱݱ‬Δɻ

ࢠ͸ऑ͘ඪ४໛‫ͱࢠཻܕ‬૬‫͢༻࡞ޓ‬ΔͷͰ, ௕ण໋ͱͳ

ʮ༏Εͨ୳ࡧ‫౓ײ‬ʯʹ͍ͭͯ͸, LHC ͷཅࢠɾཅࢠি

ΔɻͦͷͨΊ, ৽ཻࢠͷ่յաఔΛัΒ͑ΔͨΊʹ͸, ‫ݕ‬ઃஔ͠ͳ͚Ε͹ͳΒͳ͍ɻTI12 ͸·͞ʹ͍ܰ৽ཻࢠͷಥͰ௒લํํ޲ʹੜ੒͞ΕΔ৽ཻࢠΛର৅ͱ͢Δ͜ͱͰ,
LHC ͷߴ͍ੜ੒அ໘ੵΛ‫͖Ͱ༻׆‬Δɻ͞Βʹ, ৽ཻࢠ͕FASER ‫ݕ‬ग़‫ʹث‬΍ͬͯ͘Δ·Ͱʹ, ΄ͱΜͲͷඪ४໛୳ࡧʹ͏͚ͬͯͭͷ৔ॴͰ, ͨ·ͨ·͜ͷΑ͏ͳۭ͖ۭ

‫ࢠཻܕ‬͸‫ؠ‬ੴ΍ LHC ͷߏ੒ཁૉʹΑͬͯ‫ٵ‬ऩ͞Ε, എ͕ؒ͋ͬͨͷ͸޾͍ͩͬͨʢ͜ΕΛʮFASER ϛϥΫϧʯ‫ࣄܠ‬৅͕΄ͱΜͲͳ͍ΫϦʔϯͳ࣮‫ݧ‬Λ࣮‫͖Ͱݱ‬Δɻ͜

ͱ໊෇͚Δʣɻ

ΕʹΑͬͯ, FASER ‫ݕ‬ग़‫ث‬͸ίϯύΫτͰ͋Δʹ΋ؔग़‫ث‬͸ϏʔϜিಥ఺͔Β਺ඦϝʔτϧҎ্཭Εͨ৔ॴʹ

FASER ‫ݕ‬ग़‫ث‬͸, ௚‫ܘ‬໿ 20 cm, શ௕ 5 m ͷେ͖͞ΘΒͣ, ଞͷ‫ܭ‬ըதͷ࣮‫ͱݧ‬ಉఔ౓ͷ୳ࡧ‫౓ײ‬Λ࣮‫͢ݱ‬

Ͱ͋Δɻ‫ݕ‬ग़‫ث‬ཁૉͱͯ͠͸, ඈ੻‫ݕ‬ग़‫ث‬, ΧϩϦϝʔΔ͜ͱ͕Ͱ͖Δɻ͜Εʹ͍ͭͯ͸࣍ষͰৄ͘͠ड़΂Δɻλ, γϯνϨʔλ‫ݕ‬ग़‫ͱث‬, 0.5 T ͷӬ‫ٱ‬μΠϙʔϧ࣓ੴͰߏ੒͞ΕΔʢਤ 3ʣɻ‫ݕ‬ग़‫ث‬ͷ্ྲྀʹ 150 cm ௕ͷ

0.5 T Ӭ‫ٱ‬μΠϙʔϧ࣓ੴ͕͋Γ, ͜Ε͕৽ཻࢠͷ่յϘϦϡʔϜͷ໾ׂΛՌͨ͢ɻͦͷ‫ޙ‬Ζʹ, ͞Βʹ 2 ୆ͷ

100 cm ௕ͷ 0.5 T Ӭ‫ٱ‬μΠϙʔϧ࣓ੴΛઃஔ͠, εϖΫτϩϝʔλͱͯ͠࢖༻͢Δɻ֤࣓ੴͷؒʹ 3 ͭͷඈ੻‫ݕ‬ग़‫ث‬εςʔγϣϯ͕͋Γ, ৽ཻࢠ่͕յͯ͠Ͱ͖ͯͨՙ
ిཻࢠΛัΒ͑Δɻ࠷ԼྲྀͷΧϩϦϝʔλΛ༻͍ͯ, ిࢠͷಉఆ, ΤωϧΪʔଌఆ, τϦΨʔൃߦΛߦ͏ɻ·ͨ,FASER ‫ݕ‬ग़‫ث‬ͷ࠷্ྲྀʹઃஔ͢ΔγϯνϨʔγϣϯ‫ݕ‬

3.2

୳ࡧ‫౓ײ‬ͷ‫ੵݟ‬΋ΓϕϯνϚʔΫͱͯ͠, ҉ࠇϑΥτϯʢA� ʣ͕ FASER ‫ݕ‬ग़‫ࢠిͰ಺ث‬ରʹ่յ͢ΔաఔʢA� → e+ e− ʣΛัΒ͑Δ͜ͱΛߟ͑Δɻਤ 4 ͸, ҉ࠇϑΥτϯʹର͢Δ FASER
࣮‫ݧ‬ͷ‫ྖ౓ײ‬Ҭͱ, ͜Ε·Ͱʹ୳ࡧ͞ΕͨഉআྖҬΛ͍ࣔͯ͠Δɻԣ࣠͸҉ࠇϑΥτϯͷ࣭ྔʹͳ͍ͬͯͯ, ॎ࣠͸҉ࠇϑΥτϯͱ γ ͷࠞ߹ύϥϝʔλ (�) Ͱ͋ΔɻάϨʔͷྖҬ͕͜Ε·Ͱʹഉআ͞Ε͓ͯΓ, 300 MeV ҎԼ

3
75

10-3

LHCb D*

10-4

HPS

LHCb A'

SeaQuest

10-5ͷ҉ࠇϑΥτϯ͕ � = 10−5 Ͱ γ ͱࠞ߹͢ΔͱԾఆͯ͠,FASER ࣮‫Ͱݧ‬ಘΒΕΔ৴߸ࣄ৅਺Λ‫ੵݟ‬΋ͬͯΈΔɻ
LHC ͷ Run3 Ͱ૝ఆ͞Ε͍ͯΔ 14 TeV ͷཅࢠɾཅࢠ
িಥͰ 150 fb−1 ͷੵ෼ϧϛϊγςΟ͕ಘΒΕΔͱԾఆ
͢Δͱ, ໿ 2.3 × 1017 ͷ π 0 ͕ੜ੒͞ΕΔɻͳ͓, Run3

ʹ͓͚Δ LHC ͷΤωϧΪʔ͕Ծʹ 13 TeV ͷ··Ͱ΋,ཅࢠɾཅࢠඇ஄ੑࢄཚͷஅ໘ੵ͸΄΅ಉ͡ͳͷͰ, π 0 ऩྔ͸େ͖͘มΘΒͳ͍ɻੜ੒͞Εͨ π 0 ͷ͏ͪ, 0.6%͕

FASER ‫ݕ‬ग़‫ث‬ͷΞΫηϓλϯεʹऩ·Δɻπ 0 → A� γͷ่յ෼‫ذ‬ൺ͸ �2 = 10−10 Ͱ, A� ͕‫ݕ‬ग़‫ࢠిͰ಺ث‬ରʹ่յ͢Δ֬཰͕ 10−3 Ͱ͋ΔɻҎ্ͷ਺ࣈΛֻ͚߹ΘͤΔͱ, ໿ 100 ࣄ৅ͷ A� →SHiP

150 fb -1

10-2

ͷ҉ࠇϑΥτϯʹ͍ͭͯ͸, ֓Ͷ � = 10−6 ∼ 10−3 ͕୳ࡧ͢΂͖ྖҬͰ͋Δ͜ͱ͕Θ͔Δɻ͜͜Ͱ͸, 100 MeV

10 fb -1

10-6 Dark Photonਤ 3: FASER ‫ݕ‬ग़‫ث‬ͷ֓೦ਤɻӈख͕ ATLAS ࣮‫ݧ‬ͷϏʔϜিಥ఺ͷํ޲ɻ

Belle-II

NA62

10-1
mA' [GeV]ਤ 4: FASER ࣮‫͚͓ʹݧ‬Δ҉ࠇϑΥτϯʹର͢Δ‫౓ײ‬ͷ‫ੵݟ‬΋Γɻԣ࣠͸৽ཻࢠͷ࣭ྔ, ॎ࣠͸҉ࠇϑΥτϯͱγ ͷࠞ߹ύϥϝʔλΛද͢ɻάϨʔͷྖҬ͸, ిࢠɾཅిࢠিಥ‫ݧ࣮ܕ‬΍ϏʔϜμϯϓ࣮‫ʹͲͳݧ‬Αͬͯഉআ͞Ε͍ͯΔ [14]ɻ10 fb−1 ͸ 2021 ೥Ͱ, 150 fb−1 ͸ LHC
ͷ Run3 ͷશ‫Ͱؒظ‬औಘՄೳͳੵ෼ϧϛϊγςΟɻ
ͱ͍ͯ͠Δ෺ཧଌఆ͕ҟͳΔɻͦͷͨΊ, ৽ཻࢠ୳ࡧͷͨΊʹ͸‫ݕ‬ग़‫ث‬ͷվྑ͕ඞཁͱͳΔ͕, ·ͩ۩ମతͳ࣮
ࢪ‫ܭ‬ը͸ͳ͍ɻҎ্ͷঢ়‫گ‬Λ౿·͑Δͱ, ͜ͷ୳ࡧྖҬʹ͍ͭͯ, ѹ౗తʹૣ͘୳ࡧΛ࣮‫͖Ͱݱ‬Δͷ͕ FASER
࣮‫͋Ͱݧ‬Δɻ

e+ e− աఔ͕‫ݕ‬ग़‫ൃͰ಺ث‬ੜ͠, FASER ࣮‫ेͰݧ‬෼ʹ‫؍‬ଌͰ͖Δ͜ͱ͕෼͔Δɻ‫ݕ‬ग़‫ث‬ͷαΠζ͕খͯ͘͞΋,ߴ͍୳ࡧ‫౓ײ‬Λ࣋ͭ͜ͱ͕Ͱ͖Δͷ͸, ͻͱ͑ʹ௒લํํ޲ͷཅࢠɾཅࢠඇ஄ੑࢄཚͷஅ໘ੵ͕ߴ͍͜ͱʹΑΔɻ

LHC Run3 ͷ࠷ॳͷ೥Ͱ͋Δ 2021 ೥͸, ॠؒϧϛϊγςΟ͕௿͘, ໿ 20 fb−1 ͷσʔλΛऔಘ͢Δ༧ఆʹͳͬ
͍ͯΔɻਤ 4 Λ‫ͯݟ‬ΈΔͱ, ࠷ॳͷ೥ͷσʔλ͚ͩͰ΋,FASER ࣮‫Ͱݧ‬ະ୳ࡧྖҬΛ։୓Ͱ͖Δ͜ͱ͕෼͔Δɻ͞Βʹ, Run3 ͷશ‫Ͱؒظ‬औಘ༧ఆͷ໿ 200 fb−1 ͷσʔλΛ༻͍Δͱ, ҉ࠇϑΥτϯʹ͍ͭͯͷ୳ࡧྖҬΛେ෯ʹ֦େͰ͖Δɻ͜͜Ͱ஫໨͍ͨ͠ͷ͸, Belle II ͱ LHCb ͸ FASER
࣮‫ݧ‬ΑΓ΋େ͖ͳ݁߹ྖҬʹ‫౓ײ‬Λ࣋ͪ, FASER ࣮‫ݧ‬ͱΑ͍૬ิؔ܎ʹ͋Δ͜ͱͰ͋Δɻ͜ΕΒͷ࣮‫ͱݧ‬૊Έ߹ΘͤΔͱ, 100 MeV ҎԼͷ҉ࠇϑΥτϯʹ͍ͭͯ, ΄
΅શͯͷ݁߹ྖҬΛ୳ࡧͰ͖Δɻͳ͓, ਤ 4 தʹ͋Δ SHiP[11], SeaQuest[12], NA62[13]͕ FASER ࣮‫ͱݧ‬ಉ͡ྖҬʹ‫౓ײ‬Λ͍࣋ͬͯΔɻ͔͠͠,SHiP ͸‫ܭ‬ըதͷ࣮‫Ͱݧ‬, ‫ݐ‬ઃ༧ࢉͷ໨్ཱ͕͍ͬͯͳ
͍ɻSeaQuest ͱ NA62 ͸Քಇதͷ࣮‫͋Ͱݧ‬Δ͕, ओ‫؟‬3.3

എ‫ࣄܠ‬৅ͷ‫ੵݟ‬΋Γཅࢠɾཅࢠিಥ‫ݯى‬ͷඪ४໛‫ࢠཻܕ‬͸, FASER ࣮‫ݧ‬ϗʔϧʹ΍ͬͯ͘Δ·Ͱʹ‫ؠ‬൫΍ LHC ͷՃ଎‫ث‬ཁૉʹΑͬͯ΄ͱΜͲ‫ٵ‬ऩ͞ΕΔɻͦͷͨΊ, ओͳഎ‫ࣄܠ‬৅͸ߴΤωϧΪʔͷϛϡʔΦϯࣄ৅Ͱ͋Δɻͳ͓, χϡʔτϦϊࣄ৅͸, FASER ࣮‫Ͱݧ‬͸ແࢹͰ͖Δ΄Ͳগͳ͍ɻ
ਤ 5 ͸, FLUKA γϛϡϨʔγϣϯΛ༻͍ͨ FASER
࣮‫ݧ‬ϗʔϧʹ͓͚ΔϛϡʔΦϯɾϑϥοΫεͷ‫ੵݟ‬΋ΓͰ͋Δɻগ͠‫͕͍͘ʹ͑ݟ‬, ࠇͷઢͰ FASER ‫ݕ‬ग़‫ث‬͕ઃஔ͞ΕΔτϯωϧ͕ࣔ͞Ε͍ͯΔɻ͞Βʹ, τϯωϧ಺ଆͷӈ୺ʹখ͘͞ઔ‫ܕ‬ͷઢ͕ඳ͔Ε͍ͯͯ, ͜Ε͕

FASER ‫ݕ‬ग़‫͕ث‬ઃஔ͞ΕΔ৔ॴʹରԠ͢ΔɻLHC Ճ଎‫ث‬ͷ࣓৔ʹΑͬͯ, μ− ͸ਤͷࠨଆʹ, μ+ ͸ӈଆʹ‫͛ۂ‬ΒΕΔɻ͜ͷਤΛ‫ݟ‬Δͱ, ϛϡʔΦϯ͸ஸ౓ FASER ‫ݕ‬ग़‫ث‬ΛΑ͚ΔΑ͏ʹ෼෍͍ͯ͠Δ͜ͱ͕෼͔Δɻैͬͯ,FASER ‫ݕ‬ग़‫ث‬Λઃஔ͢Δ৔ॴͰ͸, ‫੻ح‬తʹഎ‫ࣄܠ‬৅͕࠷খ‫ʹݶ‬཈͑ΒΕ͍ͯΔ͜ͱ͕෼͔Δʢ͜Ε΋ FASER
ϛϥΫϧʣɻ
҉ࠇϑΥτϯͷ৔߹, ‫ݕ‬ग़‫Ͱ಺ث‬ͷ่յʹΑΔిࢠͱ

476

ਤ 6: ඈ੻‫ݕ‬ग़‫ث‬ͷୈ 2 ͱୈ 3 εςʔγϣϯʹ͓͚Δ, ҉ࠇϑΥτϯ͔Βͷӡಈྔ͝ͱͷిࢠͱཅిࢠτϥοΫͷ
‫཭ڑ‬ɻ҉ࠇϑΥτϯͷ࣭ྔ͸ 100 MeV ΛԾఆ͍ͯ͠Δɻ
Λఏग़ͨ͠ɻͦͯ͠, ͍ͭʹ 2019 ೥ 3 ݄ʹ CERN ͔Β LHC ࣮‫ͯ͠ͱݧ‬ͷঝೝΛड͚, ຊ֨తʹ‫ݐ‬ઃʹ޲͚ͨ४උΛ։࢝ͨ͠ɻFASER ࣮‫ݧ‬ͷ‫ݐ‬ઃͱӡసͷͨΊͷ༧ࢉ͸, ΞϝϦΧͷࡒஂͰ͋Δ Heising-Simons ࡒஂͱ

Simons ࡒஂ͔Βશֹิॿ͞ΕΔ͜ͱʹͳͬͨɻ2019 ೥ 11 ݄‫ࡏݱ‬, FASER ίϥϘϨʔγϣϯ͸ 8 ͔
ࠃ, 18 ‫ؔػڀݚ‬, 47 ໊Ͱߏ੒͞Ε͍ͯΔɻͦͷ͏ͪ, ࣮‫ݧ‬԰͸໿൒਺Ͱ, ‫ݕ‬ग़‫͘ͳͰ͚ͩث‬ਓһ΋ίϯύΫτͰ
͋Δɻ࣮‫ݧ‬԰͸ ATLAS ࣮‫ࢀʹݧ‬Ճ͍ͯ͠Δਓ͕େ൒Ͱ,ਤ 5: FASER ࣮‫ݧ‬ϗʔϧʹ͓͚Δ μ−ʢ্ʣͱ μ+ʢԼʣͦͷ΄ͱΜͲ͕ԿΒ͔ͷΤΩεύʔτͰ͋Δɻͱ͍͏ΑͷϑϥοΫεͷ‫ੵݟ‬΋ΓɻτϯωϧͷӈԼʹখ͘͞ඳ͔

Γ΋, ֤ํ໘ͷΤΩεύʔτΛҰຊ௼Γ͖ͯͨ͠ͱ͍ͬ

Ε͍ͯΔઔ‫ ͕ܕ‬FASER ‫ݕ‬ग़‫ث‬ͷҐஔɻͨํ͕ਖ਼͍͠ɻͦͷͨΊ, গ਺ਫ਼ӶͰεϐʔυ‫ײ‬Λ࣋ͬཅిࢠͷ 2 ͭͷτϥοΫ͕৴߸ͱͳΔɻͦͷͨΊ, ϛϡʔΦϯͷ੍ಈ์ࣹʹΑΔ γ ͕, ‫ݕ‬ग़‫ࢠిͰ಺ث‬ɾཅిࢠରੜ
੒Λ‫͜͠ى‬, ͞ΒʹϛϡʔΦϯΛ‫ݕ‬ग़Ͱ͖ͳ͔ͬͨ৔߹

࣮ͯ‫ݧ‬ͷ४උ͕ਐΜͰ͍Δɻ4 અͰզʑ͕‫ܞ‬Θ͍ͬͯΔ
ඈ੻‫ݕ‬ग़‫ث‬ͷ։ൃʹ͍ͭͯ, 5 અͰඈ੻‫ݕ‬ग़‫ث‬Ҏ֎ͷ४උঢ়‫͍ͯͭʹگ‬ड़΂Δɻ͸, ‫ͯͬޡ‬৴߸ࣄ৅ͱͯ͠ೝࣝ͞ΕΔɻγϛϡϨʔγϣϯʹΑΔͱ, 100 GeV Ҏ্ͷ γ ΋͘͠͸ϋυϩϯγϟ
ϫʔΛ൐͏ϛϡʔΦϯࣄ৅͸, Run3 ͷશ‫Ͱؒظ‬໿ 80k
ࣄ৅Ͱ͋Δɻ͜Ε͸ 5.2 અͰ঺հ͢Δ veto εςʔγϣϯʹΑͬͯ, े෼ʹམͱ͢͜ͱ͕Ͱ͖ΔϨϕϧͰ͋Δɻ

FULKA ͷγϛϡϨʔγϣϯ݁ՌΛ֬ೝ͢ΔͨΊ,
LHC Run2 ӡసதͷ 2018 ೥ʹΤϚϧγϣϯΛ FASER
࣮‫ݧ‬ͷ৔ॴʹઃஔͨ͠ɻଌఆ݁Ռ͸ FULKA ͷ༧૝ͱΑ͘Ұக͍ͯ͠Δ͜ͱ͕֬ೝͰ͖ͨɻ

4ඈ੻‫ݕ‬ग़‫ث‬

4.1

֓ཁ

FASER ‫ݕ‬ग़‫࠷Ͱث‬΋ॏཁͳ໾ׂΛ୲͏ͷ͕, ඈ੻‫ݕ‬ग़‫͋Ͱث‬Δɻਤ 6 ͸, 100 MeV ͷ࣭ྔΛ΋ͬͨ҉ࠇϑΥτϯ͕ిࢠରʹ่յͨ͠৔߹ͷ, ඈ੻‫ݕ‬ग़‫͚͓ʹث‬Δి
ࢠɾཅిࢠͷ‫཭ڑ‬Λද͍ͯ͠Δɻ͜ΕΛ‫ݟ‬Δͱ, ୈ 2 εςʔγϣϯͰ 300 μm ఔ౓ͷඈ੻෼཭ೳྗ͕͋Ε͹, ΄
΅શͯͷ҉ࠇϑΥτϯΛัΒ͑Δ͜ͱ͕Ͱ͖Δ͜ͱ͕෼

3.4‫ݐ‬ઃ։࢝·ͰͷಓͷΓ

FASER ࣮‫ݧ‬͸ 2017 ೥ʹఏҊΛߦ͍, 2018 ೥ 7 ݄ʹLetter Of Intent Λ, 2018 ೥ 11 ݄ʹ Technical Proposal͔ΔɻͦͷͨΊ, ඈ੻‫ݕ‬ग़‫ʹث‬͸ 300 μm ΑΓ༏ΕͨҐஔ෼ղೳ͕‫ٻ‬ΊΒΕΔɻ͜ͷཁ‫ٻ‬Λຬͨͨ͢Ί, FASER
࣮‫Ͱݧ‬͸γϦίϯɾετϦοϓ‫ݕ‬ग़‫ث‬Λ࢖༻͢Δ͜ͱʹ
ͨ͠ɻ

5
77

ਤ 7: ATLAS SCT όϨϧɾϞδϡʔϧɻηϯαʔ্໘ʹ഑ஔ͞Ε͍ͯΔͷ͕ϋΠϒϦουͰ, ASIC ͸ද໘ʹ

6 ‫ݸ‬, ཪ໘ʹ 6 ‫ݸ‬౥ࡌ͞Ε͍ͯΔɻϋΠϒϦουͷԼ୺ʹ͋ΔίωΫλ͔Β৴߸ΛಡΈग़͢ɻඈ੻‫ݕ‬ग़‫ʹث‬͸ ATLAS ‫ݕ‬ग़‫ ث‬SCT ͷόϨϧྖҬʹ࢖༻͞Ε͍ͯΔ, γϦίϯɾετϦοϓ‫ݕ‬ग़‫ث‬ͷεϖΞɾϞδϡʔϧΛ࢖༻͢Δ (ਤ 7)[15]ɻηϯαʔ͸ p-in-n ‫Ͱܕ‬,

63.3×64 mm2 ͷେ͖͞Ͱ͋ΔɻSCT Ϟδϡʔϧ͸, ย໘ਤ 8: ඈ੻‫ݕ‬ग़‫ث‬εςʔγϣϯͷ֓೦ਤɻ3 ϨΠϠʔͰ

1 εςʔγϣϯΛߏ੒͍ͯ͠ΔɻͦΕͧΕͷϞδϡʔϧʹ઀ଓ͞Ε͍ͯΔϑϨΩγϒϧ‫ج‬൘͸, ϨΠϠʔͷ྆୺ʹ഑ஔ͞Ε͍ͯΔύονύωϧʹ઀ଓ͞ΕΔɻ

4.2

Ϟδϡʔϧબผ

ʹηϯαʔ 2 ຕΛ࢖༻͠, ͦΕΛཪදʹ 40 mrad ͷεςඈ੻‫ݕ‬ग़‫ث‬ͷ։ൃͷͨΊʹ, εϖΞΛ‫ؚ‬Ίͯશ෦ͰϨΦ֯Λ͚ͭͯϖΞͱ͢Δɻͦͯ͠, ASIC(ABCD νοϓ [16]) Λ 12 ‫ݸ‬౥ࡌͨ͠ϋΠϒϦουΛηϯαʔͱϫΠ10 ϨΠϠʔΛ࡞੒͢ΔɻͦͷͨΊʹ͸, 80 ‫ݸ‬ͷ SCT Ϟδϡʔϧ͕ඞཁͱͳΔɻ্‫ه‬ͷͱ͓Γ, ATLAS SCT άϠʔɾϘϯυͰ઀ଓ͢Δ͜ͱͰ, Ϟδϡʔϧ͕ग़དྷ্͕Δɻϧʔϓͷ޷ҙʹΑͬͯ, ໿ 200 ‫͋ݸ‬ΔεϖΞɾϞδϡʔετϦοϓɾϐον͸ 80 μm Ͱ, Ϟδϡʔϧย໘Ͱ 768√
ετϦοϓͰ͋ΔɻҐஔ෼ղೳ͸, 80 μm/ 12 ∼ 23 μmϧ͔Β࠷ྑͷ 80 ‫ݸ‬ΛબΜͰ࢖༻ͯ͠ྑ͍͜ͱʹͳͬͨɻͱͳΓ, ཁ‫ٻ‬ੑೳͰ͋Δ 300 μm ͷҐஔ෼ղೳΑΓ΋ҰܻҎ্ྑ͍ɻ

ͦ͜Ͱ, զʑ͕த৺ͱͳͬͯ, ඈ੻‫ݕ‬ग़‫͢༻࢖ʹث‬ΔϞδϡʔϧΛબผ͢Δ͜ͱʹͳͬͨɻ·ͣ, ࢼ‫ݧ‬γεςϜΛ୳͞ͳͯ͘͸ͳΒͳ͍ɻFASER

FASER ඈ੻‫ݕ‬ग़‫Ͱث‬͸, ͜ͷϞδϡʔϧ 8 ͭΛ࢖࣮ͬ‫ݧ‬͸, Կ΋ͳ͍ঢ়ଶ͔Β໿ 1 ೥ؒͰ࣮‫ػ‬Λ‫׬‬੒ͤ͞ͳͯ, 1 ຕͷϨΠϠʔΛ࡞੒͢Δɻͦͯ͠, 3 ϨΠϠʔΛ 1͚Ε͹ͳΒͳ͍ϓϩδΣΫτͰ͋Δɻ͞Βʹ, લड़ͷ௨ͭͷεςʔγϣϯʹ·ͱΊͨ΋ͷΛશ෦Ͱ 3 ͭ༻͍ΔΓ, ਓһ͕ඇৗʹ‫ݶ‬ΒΕ͍ͯΔɻैͬͯ, Ϟδϡʔϧબผ(ਤ 8)ɻ֤Ϟδϡʔϧʹ͸ϑϨΩγϒϧ‫ج‬൘͕઀ଓ͞Ε,ͷͨΊʹ৽ͨͳࢼ‫ݧ‬γεςϜΛ։ൃ͢ΔΏͱΓ͸ͳ͍ɻి‫ؾ‬ઢΛϨΠϠʔͷ֎෦ʹҾ͖ग़ͯ͘͠Δͷʹ࢖༻͞ΕͦͷΑ͏ͳঢ়‫گ‬ͷத, έϯϒϦοδେֶ͕ಉ͡ SCT

Δɻύονύωϧ͸ϑϨΩγϒϧ‫ج‬൘, DAQ γεςϜ,ϞδϡʔϧΛ༻͍ͨ, ϛϡʔΦϯɾτϞάϥϑΟʔͷͨి‫ݯ‬γεςϜͷΠϯλʔϑΣʔεͷ໾ׂΛ୲͏ɻ2 ຕͷΊͷଌఆ‫ث‬Λ։ൃ͍͍ͯͯ͠Δ͜ͱ͕Θ͔ͬͨɻަবͷύονύωϧΛϨΠϠʔͷ྆୺ʹઃஔ͠, ͦΕͧΕ 4 ͭ຤, ൴Βͷࢼ‫ݧ‬γεςϜ [17] ΛҰࣜିͯ͠΋Β͏͜ͱʹͷϑϨΩγϒϧ‫ج‬൘ͱ઀ଓ͢Δɻ

ͳͬͨɻ͔͠͠, ͜ͷࢼ‫ݧ‬γεςϜΛಋೖͯ͠Έͨͱ͜ATLAS ࣮‫ݧ‬ͷΑ͏ʹ์ࣹઢଛই͕େ͖͍࣮‫Ͱڥ؀ݧ‬Ζ, ϊΠζଌఆͳͲͷ‫ج‬ຊతͳଌఆ߲໨͕࣮૷͞Ε͍ͯ͸, γϦίϯɾηϯαʔ͸ΞχʔϧޮՌΛԡ͑͞ΔͨΊʹ,ͳ͍͜ͱ͕൑໌ͨ͠ɻͦͷͨΊ, զʑͱέϯϒϦοδେ◦−20 C ఔ౓ͷ௿Թʹྫྷ΍͢ඞཁ͕͋Δɻ͔͠͠, FASER

࣮‫Ͱݧ‬͸์ࣹઢଛই͸໰୊ʹͳΒͳ͍ͷͰ, ྫྷ٫͸ਫྫྷͰߦ͏ɻϨΠϠʔͷΞϧϛɾϑϨʔϜʹ͸ྫྷ٫ੁ͕ຒΊࠐ·Ε͍ͯͯҰମߏ଄ͱͳ͍ͬͯΔɻֶͷֶੜ͕‫ͯ͠ྗڠ‬, ৽ͨͳ‫ػ‬ೳΛ૊ΈࠐΉͱ͍͏࡞‫ۀ‬͕ඞཁͩͬͨɻ
ඞཁ࠷௿‫ݶ‬ͷଌఆ߲໨͕४උͰ͖ͨͱ͜ΖͰ, Ϟδϡʔϧࢼ‫ݧ‬ͷͨΊͷγϑτΛ૊৫ͨ͠ʢਤ 9ʣɻϞδϡʔϧͷબ୒‫ج‬४͸, ϊΠζ͕༧૝ఔ౓ͷ஋ (໿ 1,700 e) Ͱ͋678Δ͜ͱ, ࢮ๢ετϦοϓͱϊΠδʔͳετϦοϓ͕ 7 ετϦοϓ (શετϦοϓͷ໿ 0.5%) ҎԼͰ͋Δ͜ͱ, ͱͨ͠ɻͦͯ͠, ໿ 2 ͔݄͔͚ͯ 2019 ೥ 3 ݄·Ͱʹ, ࠷ߴੑೳΛ࣋ͭ SCT Ϟδϡʔϧ 80 ‫ݸ‬Λબผ͢Δ͜ͱ͕Ͱ
͖ͨɻ

4.3

ϑϨΩγϒϧ‫ج‬൘ͱύονύωϧ

ϑϨΩγϒϧ‫ج‬൘ͱύονύωϧ (ਤ 8) ͸, FASER
࣮‫ݧ‬ͷඈ੻‫ݕ‬ग़‫ث‬ͷͨΊʹಠࣗ։ൃ͠ͳ͍ͱ͍͚ͳ͍ཁ
ૉͰ͋Δɻ͜ΕΒ͸, զʑ೔ຊάϧʔϓͷ୲౰ʹͳͬͯ
͍ΔɻϑϨΩγϒϧ‫ج‬൘ͷ࠷ॳͷࢼ࡞඼͸, 2019 ೥ 8 ݄ʹ‫׬‬੒ͨ͠ɻ͔͠͠, ճ࿏ਤͱ‫ݟ‬ൺ΂ͯΈΔͱ, ‫਺ح‬ϐϯͱ‫਺ۮ‬ϐϯ͕‫ج‬൘্Ͱ൓సͯ͠઀ଓ͞Ε͍ͯΔ͜ͱ͕൑໌
ͨ͠ɻͦ͜Ͱ, ‫ٸ‬ᬎमਖ਼൛Λ࡞੒͠, ཌ݄ʹ͸࢓༷Ͳ͓Γͷ΋ͷΛ‫׬‬੒ͤ͞Δ͜ͱ͕Ͱ͖ͨɻ

2019 ೥ 9 ݄ʹ‫׬‬੒ͨ͠ύονύωϧͷࢼ࡞඼Ͱ΋୯७ϛε͕ൃੜͨ͠ɻ1 ຕͷύονύωϧʹ, 1 ϨΠϠʔͷ൒෼ͷ 4 Ϟδϡʔϧ͕઀ଓ͞ΕΔɻϨΠϠʔ಺ͰϞδϡʔϧ͸, ཪද͕ަ‫ʹޓ‬഑ஔ͞Ε͍ͯΔɻͦΕʹͱ΋ͳͬͯ,ϋΠϒϦουͷίωΫλ΋ಉ༷ʹදཪͷॱʹ഑ஔ͞Ε
Δɻ͔͠͠, ύονύωϧͷίωΫλ͸ಉ͡໘ʹ഑ஔ͞ਤ 10: ඈ੻‫ݕ‬ग़‫ث‬ͷϓϩτλΠϓɾϨΠϠʔ (্) ͱ, ಡΕ͍ͯΔͷͰ, 2 छྨͷϑϨΩγϒϧ‫ج‬൘Λ༻ҙ͢Δඞ

Έग़͠ࢼ‫ݧ‬ͷ༷ࢠ (Լ)ɻύονύωϧͷઃ‫ܭ‬ϛεΛิ͏

ཁ͕͋Δ (͜͜Ͱ͸, λΠϓ A ͱλΠϓ B ͱ‫)Ϳݺ‬ɻͨΊ, ΠϯλʔϑΣʔεɾέʔϒϧΛ༻͍ͯ, ύονύ͔͠͠, ͍͟ϑϨΩγϒϧ‫ج‬൘ͱύονύωϧΛ઀ଓωϧʹ 4 ϞδϡʔϧΛ઀ଓ͍ͯ͠Δɻ͢Δஈʹͳͬͯ, ϨΠϠʔ಺ͰϑϨΩγϒϧ‫ج‬൘͕λΠ
ϓ AɾλΠϓ B ͷॱ൪ͰฒΜͰ͍Δͷʹ, ύονύωϧ

ύονύωϧ͕‫׬‬੒͠, ΠϯλʔϑΣʔεɾέʔϒϧͳͰ͸λΠϓ BɾλΠϓ A ͷॱ൪ͰίωΫλ͕഑ஔ͞Εͯ

͠Ͱ 4 ϞδϡʔϧΛ઀ଓͰ͖ΔΑ͏ʹͳͬͨɻ

͍Δ͜ͱ͕൑໌ͨ͠ɻͦͷͨΊ, ಉ࣌ʹ 2 ͭͷϞδϡʔ‫ج‬൘ͷઃ‫ܭ‬Λ͢Δ্Ͱ, ϐϯ഑ஔͷ֬ೝ͸‫ج‬ຊதͷ‫ج‬ϧ͔͠઀ଓͰ͖ͳ͍ͱ͍͏͜ͱʹͳͬͯ͠·ͬͨɻԠ‫ٸ‬

ຊͰ͋Δɻ͔͠͠, ʮ‫͏ݴ‬͸қ͠, ߦ͏͸೉͠ʯͰ, Ԟ͕ॲஔͱͯ͠ΠϯλʔϑΣʔεɾέʔϒϧΛ࡞੒ͯ͠, ͳਂ͍ͱ͍͏͜ͱΛ਎ʹછΈͯ‫ͨ͡ײ‬ɻΜͱ͔ಉ࣌ʹ 4 ͭͷϞδϡʔϧΛ઀ଓͰ͖ΔΑ͏ʹͨ͠(ਤ 10)ɻͳ͓, ຊߘΛߍਖ਼தͷ 2019 ೥ 11 ݄ʹमਖ਼൛ͷ

4.4

DAQ γεςϜ

DAQ γεςϜͱͯ͠͸, δϡωʔϒେֶ͕։ൃͨ͠
GPIO Ϙʔυͱ‫ݺ‬͹ΕΔ, ൚༻ FPGA ϘʔυΛ࢖༻͢
ΔɻGPIO Ϙʔυ͸ ALTERA ࣾͷ Cyclone V A7 ͱ͍͏ FPGA Λ౥ࡌ͓ͯ͠Γ, ίϚϯυग़ྗ΍σʔλऔಘ͸શͯ͜ͷ FPGA Ͱ੍‫͞ޚ‬Ε͍ͯΔɻϑΝʔϜ΢ΣΞͷ։ൃ͸δϡωʔϒେֶ͕୲౰͍ͯ͠
Δɻ࢓༷ॻ͕ 2019 ೥ 5 ݄ʹ‫׬‬੒͠, 8 ݄ʹ͸࢖༻Մೳͳ
ϑΝʔϜ΢ΣΞ͕࢓্͕͍ͬͯΔͱ͍͏։ൃεϐʔυͰ͋Δɻ͞Βʹ, GPIO ϘʔυͱύονύωϧΛ઀ଓ͢Δ
ͨΊʹඞཁͱͳΔΞμϓλɾΧʔυ΋, δϡωʔϒେֶ͕։ൃΛ୲౰͍ͯ͠Δɻͪ͜Β΋, ϑΝʔϜ΢ΣΞͱಉ༷ͷ଎౓Ͱ‫׬‬੒ͯ͠͠·ͬͨɻιϑτ΢ΣΞ͸ϨΠϠʔਤ 9: SCT Ϟδϡʔϧͷࢼ‫ݧ‬γεςϜΛલʹ‫ه‬೦ࡱӨɻͷࢼ‫͕ͳ͠༻࢖ʹݧ‬Βঃʑʹ։ൃΛਐΊ, 2019 ೥಺ʹ‫׬‬779

੒ͤ͞Δ͜ͱΛ໨ࢦ͍ͯ͠Δɻ

4.5

ϓϩτλΠϓɾϨΠϠʔΛ༻͍ͨࢼ‫ݧ‬2019 ೥ 10 ݄ʹ, ϓϩτλΠϓɾϨΠϠʔ͕‫׬‬੒ͨ͠(ਤ 10)ɻ͜Εʹ, ϑϨΩγϒϧ‫ج‬൘ͱύονύωϧͷࢼ࡞඼Λ઀ଓͯ͠, ੑೳධՁͷͨΊͷಡΈग़͠ࢼ‫ݧ‬Λߦͬਤ 11: FASER Ͱ࢖༻͢Δ LHCb ͷ ECAL Ϟδϡʔϧɻ

͍ͯΔɻ

2 mm ްͷԖͱ 4 mm ްͷϓϥενοΫɾγϯνϨʔλಡΈग़͠ࢼ‫Ͱݧ‬͸, ϑϨΩγϒϧ‫ج‬൘ͱύονύωϧ

ͷαϯυΠον૚͕ 66 ຕฒ΂ͨߏ଄ʹͳ͍ͬͯͯ, ௕ʹ্‫ه‬ͷ໰୊͕͋ͬͨ΋ͷͷ, ΠϯλʔϑΣʔεɾέʔखํ޲ʹ೾௕ม‫׵‬ϑΝΠόʔ͕ 64 ຊ͍ࢗͬͯ͞Δɻ

ϒϧΛ༻͍ͯ, ϨΠϠʔ಺ͷ 8 ͭͷϞδϡʔϧͱ઀ଓͰ͖ΔΑ͏ʹͳͬͨɻͦͯ͠, શϞδϡʔϧΛίϯϑΟά

ి࣓ΧϩϦϝʔλʹ͍ͭͯ͸, ‫ʹط‬શͯͷ‫ݕ‬ग़‫ث‬ཁૉ͠, σʔλΛಡΈग़͢͜ͱʹ੒ޭͨ͠ɻ͜ΕʹΑΓ, ϑͷ૊Έཱ͕ͯ‫͍ͯྃ͠׬‬Δɻ‫ࡏݱ‬͸, CERN ͷςετϕ

ϨΩγϒϧ‫ج‬൘ͱύονύωϧ‫ʹڞ‬, ྔ࢈ͷͨΊͷ४උϯνͰಈ࡞ࢼ‫ߦ͕ݧ‬ΘΕ͍ͯΔɻ͕੔ͬͨɻ͜ͷࢼ‫Ͱݧ‬͸, DAQ ͷϑϧɾνΣΠϯͰ 8 ϞδϡʔϧΛಡΈग़͢͜ͱ͕Ͱ͖Δ͔, ͱ͍͏͜ͱ͚ͩͰͳ͘, ྫྷ٫ޮ཰Λ֬ೝ͢Δ͜ͱ΋ॏཁͳ՝୊Ͱ͋Δɻඈ੻‫ݕ‬ग़‫ث‬ͷྫྷ٫͸ 15◦ C ͷਫྫྷͰߦ͏ɻӡస࣌ʹϞδϡʔϧͷԹ
౓͕ 30◦ C ҎԼʹͳΔΑ͏ʹ, ϨΠϠʔɾϑϨʔϜΛઃ‫͚ͳ͠ܭ‬Ε͹ͳΒͳ͍ɻྫྷ٫૷ஔͷઃఆԹ౓ͱྲྀྔΛม͑ͳ͕Β, ϞδϡʔϧͷԹ౓Λଌఆ͠, ྫྷ٫ޮ཰ͷ֬ೝΛߦͬͨɻͦͷ݁Ռ, े෼ͳྫྷ٫ೳྗ͕ಘΒΕΔ͜ͱ͕
෼͔ͬͨɻ

5.2

γϯνϨʔλ‫ݕ‬ग़‫ث‬γϯνϨʔλ‫ݕ‬ग़‫ث‬͸, veto εςʔγϣϯ, τϦΨʔɾεςʔγϣϯ, ϓϨγϟϫʔɾεςʔγϣϯ, ͷ 3 εςʔγϣϯ͔ΒͳΔ (ਤ 12)ɻveto εςʔγϣϯ͸ FASER ‫ݕ‬ग़‫ث‬ͷ࠷্ྲྀʹઃஔ͞Ε, ཅࢠɾཅࢠিಥ‫ݯى‬ͷϛϡʔΦϯͳͲ, FASER ‫ݕ‬ग़‫ث‬ͷ֎͔Β΍ͬͯ͘Δഎ‫ࣄܠ‬৅Λ veto ͢ΔͨΊʹ࢖༻͢ΔɻτϦΨʔɾεςʔγϣϯ͸่յϘϦϡʔϜͱඈ੻‫ݕ‬ग़‫ث‬ͷୈ 1 εςʔγϣϯͷ௚‫ʹޙ‬ઃஔ͞Ε, ৴߸ࣄ৅ͷτϦΨʔʹ࢖༻͞ΕΔɻ࠷‫ޙ‬ͦͷଞͷ४උঢ়‫گ‬55.1

ి࣓ΧϩϦϝʔλͷϓϨγϟϫʔɾεςʔγϣϯ͸, ΧϩϦϝʔλͷखલʹઃஔ͞Ε, ΧϩϦϝʔλલͰൃੜͨ͠ γ ͱ ΧϩϦϝʔλ಺Ͱ‫ͨͬ͜ى‬χϡʔτϦϊࣄ৅ͱࣝผ͢ΔͨΊʹ࢖༻͢Δɻి࣓ΧϩϦϝʔλʹ͸ LHCb ͷ ECAL Ϟδϡʔϧͷ

veto εςʔγϣϯͱϓϨγϟϫʔɾεςʔγϣϯ͸ͦεϖΞΛ࢖༻͢Δ (ਤ 11)[18]ɻΧϩϦϝʔλɾϞδϡʔΕͧΕ, 2 cm ͷްΈͰ, 30 × 30 cm2 ͷେ͖͞ͷϓϥε2

ϧ͸, 121.2 × 121.2 mm ͷஅ໘ੵͰ, PMT ΛೖΕͯνοΫɾγϯνϨʔλ (Bicron BC 408) Λ 4 ϨΠϠʔ࢖

754 mm ͷ௕͞Ͱ͋Δɻͦͯ͠, 2 mm ްͷԖͱ 4 mm

༻͢Δɻͦͯ͠, γϯνϨʔλͷยଆʹϥΠτɾΨΠυްͷϓϥενοΫɾγϯνϨʔλͷαϯυΠον૚ΛΛऔΓ෇͚, ඿দϑΥτχΫεࣾ੡ͷ PMT(H6410) ʹ

66 ຕฒ΂ͨߏ଄ʹͳ͍ͬͯΔɻ௕खํ޲ʹ೾௕ม‫׵‬ϑΝ઀ଓ͢ΔɻFASER ‫ݕ‬ग़‫Ͱث‬͸, എ‫ࣄܠ‬৅Λআ‫͢ڈ‬Δͨ

Πόʔ͕ 64 ຊ͓ࢗͬͯ͞Γ, ͦΕΛ 1 ͭͷଋʹ·ͱΊΊʹ, veto εςʔγϣϯͷ 1 ϨΠϠʔʹ͸ 98%Ҏ্ͷ‫ݕ‬

ͯ PMT Ͱ·ͱΊͯಡΈग़͢ɻશମͰ 25 ์ࣹ௕Λ࣋ͪ,ग़ޮ཰͕ཁ‫͞ٻ‬ΕΔ͕, 2 cm ͷްΈΛ֬อ͢Δ͜ͱͰ

TeV ͷΤωϧΪʔଛࣦʹରͯ͠, ໿ 1%ͷΤωϧΪʔ෼99.99%Ҏ্ͷ‫ݕ‬ग़ޮ཰Λ࣋ͨͤΔ͜ͱ͕Ͱ͖ΔɻղೳΛ࣮‫͖Ͱݱ‬ΔɻFASER ࣮‫Ͱݧ‬͸͜ͷϞδϡʔϧΛ

4 ͭ༻͍ͯ, ి࣓ΧϩϦϝʔλΛߏ੒͢Δɻ
PMT ʹ͸ LHCb Ͱ࢖༻͞Ε͍ͯΔ΋ͷͱಉ͡඿দϑFASER ‫ݕ‬ग़‫֎ث‬෦͔Β΍ͬͯ͘Δ γ ΛัΒ͑ΔͨΊʹ, veto εςʔγϣϯʹ͸ 15 × 30 × 30 cm3 ͷԖϒϩοΫΛஔ͘ɻ͜ΕʹΑΓ, ϛϡʔΦϯͷ੍ಈ์ࣹʹΑΔ γΥτχΫεࣾ੡ͷޫిࢠ૿ഒ؅ (PMT: PhotoMutiplierΛ‫ٵ‬ऩͯ͠͠·͏͔, ຢ͸γϟϫʔΛ‫ͯͤ͜͞ى‬γϯνTube) Ͱ͋Δ R7899-20 Λ࢖༻͢Δɻσʔλऔಘ͸ 16ϨʔλͰัΒ͑Δ͜ͱ͕Ͱ͖ΔɻϓϨγϟϫʔɾεςʔνϟϯωϧ CAEN σδλΠβʔɾϘʔυ (VX1730) Ͱγϣϯʹ͸, γ γϟϫʔΛ‫ͤ͜͞ى‬ΔͨΊʹ, 1 ์ࣹ௕ʹߦ͏ɻ͜Ε͸, γϯνϨʔγϣϯ‫ݕ‬ग़‫ʹث‬΋༻͍Δɻσ

૬౰͢Δ໿ 5 mm ްͷԖ૚Λ 3 ຕઃஔ͢ΔɻδλΠβʔͷαϯϓϧ଎౓͸ 500 MHz Ͱ, 14 ϏοτͷτϦΨʔɾεςʔγϣϯ͸ްΈ͕ 1 cm, ໘ੵ͕ 20 ×40 cm2 ͷγϯνϨʔλΛಉ͡໘ʹ 2 ຕฒ΂ͨ 1 ϨΠϠʔ

ADC Λ࢖༻͍ͯ͠ΔɻΛ༻͍ΔɻτϦΨʔɾεςʔγϣϯ͸࣌ؒଌఆʹ΋࢖༻

880

ਤ 13: Ӭ‫ٱ‬μΠϙʔϧ࣓ੴͷ֓೦ਤ (ࠨ) ͱ࣓৔ߏ଄(ӈ)ɻࠨਤͰ, ໼ҹ͸֤ϋϧόοϋ഑ྻͷ࣓৔ͷ޲͖Λද͢ɻਤ 12: γϯνϨʔλ‫ݕ‬ग़‫ث‬ͷ֓೦ਤɻϏʔϜিಥ఺ʹ޲্͔ͬͯྲྀ͔Β, veto εςʔγϣϯ, τϦΨʔɾεςʔγϣϯ, ϓϨγϟϫʔɾεςʔγϣϯΛઃஔ͢Δɻ͠, ϏʔϜিಥ༝དྷͰͳ͍ࣄ৅Λഉআ͢ΔͨΊʹ 1 ns ͷ࣌ؒ෼ղೳΛཁ‫͢ٻ‬ΔɻͦͷͨΊ, γϯνϨʔλͷ྆୺ͰಡΈग़͠, λΠϜ΢ΥʔΫิਖ਼͕Ͱ͖ΔΑ͏ʹ͢Δɻ
ΧϩϦϝʔλಉ༷ʹγϯνϨʔλ‫ݕ‬ग़‫͍ͯͭʹث‬΋,શͯͷ‫ݕ‬ग़‫ث‬ཁૉͷ૊Έཱ͕ͯऴΘΓ, CERN ͷςετϕϯνͰಈ࡞ࢼ‫ݧ‬Λߦ͍ͬͯΔɻ

ΛัΒ͑ΔͨΊʹ͸, ࣮‫ݱݧ‬৔ͷচΛ࠷େͰ 50 cm ఔ౓
۷Δඞཁ͕͋Δ (ਤ 3)ɻ·ͨ, ిྗͷ‫څڙ‬ϥΠϯ΍ωο
τϫʔΫઃඋΛઃ͚Δ͜ͱ΋ඞཁͰ͋Δɻ‫ ࡏݱ‬LHC ͷγϟοτμ΢ϯதͰ, ༷ʑͳ LHC ͷϝΠϯςφϯε࡞‫ߦ͕ۀ‬ΘΕ͍ͯΔɻFASER ࣮‫ݧ‬ͷͨΊͷ౔໦޻ࣄ͸͜ΕΒʹ‫ׯ‬ব͠ͳ͍Α͏ʹ͠ͳ͚Ε͹ͳΒͳ͍ɻ·ͨ, চΛ۷Δࡍʹτϯωϧͷ஍ԼʹຒΊͯ͋Δഉਫ‫ܥ‬ΑΓ΋ਂ͘۷Δ͜ͱ͕Ͱ͖ͳ͍ɻ͞Βʹ, ౔໦޻ࣄʹΑΔਖͷൃੜΛ཈͑Δ͜ͱ΋ॏཁͰ͋ΔɻҎ্ͷ੍‫ݶ‬ͷதͰ࡞‫ۀ‬ΛߦΘͳ͚Ε͹ͳΒͳ͍ͷͰ,౔໦޻ࣄͷͨΊͷ࡞‫ܭۀ‬ը͕໖ີʹٞ࿦͞Ε͍ͯΔɻ͜Ε·Ͱʹ, FASER ࣮‫ʹݧ‬ෆඞཁͳ෺ࢿ͕औΓআ͔Ε, ৽5.3

Ӭ‫ٱ‬μΠϙʔϧ࣓ੴͨʹέʔϒϧɾτϨΠͱ‫ס‬૩ۭ‫ؾ‬ͷ‫څڙ‬ϥΠϯ͕ઃஔ͞ΕͨɻFASER ࣮‫࠷Ͱݧ‬ॏཁͳ୳ࡧϞʔυ͸, ҉ࠇϑΥτϯ͕ిࢠରʹ่յ͢Δࣄ৅Ͱ͋Δɻ҉ࠇϑΥτϯΛัΒ͑
ΔͨΊʹ͸, ่յϘϦϡʔϜͰ҉ࠇϑΥτϯ่͕յͯ͠
ग़͖ͯͨిࢠͱཅిࢠΛ෼཭͠, ӡಈྔΛଌఆ͢ΔͨΊͷ࣓ੴ͕ඞཁͱͳΔɻ͔͠͠, FASER ‫ݕ‬ग़‫ث‬ͷઃஔ͞ΕΔτϯωϧ಺͸εϖʔε͕‫ݶ‬ΒΕ͍ͯΔ͜ͱ΋͋Γ,ফඅిྗ΍ྫྷ٫‫ܥ‬Λ࠷খ‫ʹݶ‬཈͍͑ͨɻ
Ҏ্Λߟྀͯ͠, FASER ࣮‫Ͱݧ‬͸่յϘϦϡʔϜͱεϖΫτϩϝʔλͷͨΊʹ, 0.5 T ͷӬ‫ٱ‬μΠϙʔϧ࣓ੴΛ༻͍Δ͜ͱʹͨ͠ʢਤ 13ʣɻ͜ͷ࣓ੴ͸, 16 ‫ݸ‬ͷηΫγϣϯʹ෼͔Ε͓ͯΓ, ֤ηΫγϣϯͷ࣓৔ͷ޲͖Λௐ੔
͢Δ͜ͱͰ (ϋϧόοϋ഑ྻ), μΠϙʔϧ࣓৔Λ࣮‫͢ݱ‬Δɻ͜ͷλΠϓͷ࣓ੴ͸‫ ʹط‬CERN ͷ NTOF(Neutron

Time-Of-Flight) ͷͨΊʹ։ൃ͞Ε͓ͯΓ, FASER ࣮‫ݧ‬Ͱͦͷෳ੡ʹ͍ۙ΋ͷΛ੡࡞͢ΔɻӬ‫ٱ‬μΠϙʔϧ࣓ੴ͸ CERN ͕੡଄Λ୲౰͓ͯ͠Γ, 2020 ೥ 5 ݄ʹશͯͷ࣓ੴͷ‫׬‬੒Λ໨ࢦͯ͠, σβΠϯͷ࠷దԽ͕ߦΘΕ͍ͯΔɻ

6Πϯετʔϧ·Ͱͷࠓ‫ޙ‬ͷ༧ఆ
LHC ͸ 2020 ೥ 5 ݄͔Β, Ճ଎‫ث‬ͷྫྷ٫Λ։࢝͢ΔɻͦΕҎ߱͸, ΫϨʔϯΛ࢖ͬͨେ͖ͳ‫ݕ‬ग़‫ث‬ཁૉͷҠಈ͸Ͱ͖ͳ͘ͳΔɻͦͷͨΊ, ͦΕ·ͰʹՄೳͳ‫ݶ‬Γͷ‫ݕ‬ग़‫ث‬ཁૉΛ࣮‫ݧ‬৔ॴʹҠಈ͓ͯ͘͜͠ͱ͕๬·͍͠ɻগͳ͘ͱ΋, ΫϨʔϯ࡞‫͕ۀ‬ඞཁͱͳΔӬ‫ٱ‬μΠϙʔϧ࣓ੴ͸ઃஔ͓͔ͯ͠Ͷ͹ͳΒͳ͍ɻ

FASER ‫ݕ‬ग़‫ث‬ͷཁૉ։ൃͰ, ࠷΋࣌ؒΛඞཁͱ͢Δ
ͷ͕ඈ੻‫ݕ‬ग़‫͋Ͱث‬Δɻ2019 ೥தʹୈ 1 ϨΠϠʔͷ࡞੒ͱੑೳධՁࢼ‫ݧ‬Λऴ͑, 2020 ೥ 3 ݄·ͰʹεϖΞ 1 ຕΛ‫ؚ‬Ή, શ 10 ϨΠϠʔͷ੡଄Λߦ͏͜ͱΛ໨ࢦ͍ͯ͠Δɻඈ੻‫ݕ‬ग़‫׬͕ث‬੒͢Δͱ, 2020 ೥ 4 ݄͔Β 5 ݄ʹ͔͚ͯ, ஍্Ͱ FASER ‫ݕ‬ग़‫ث‬ͷ࠷ऴঢ়ଶͱಉ͡Α͏ʹଌఆ‫ث‬Λฒ΂, ࢼӡసΛߦ͏ɻͦͯ͠, 2020 ೥ 5 ݄ʹશͯͷ‫ݕ‬ग़‫ث‬ཁૉΛ࣮‫ݧ‬৔ॴʹઃஔ͢Δ͜ͱΛ໨ࢦ͢ɻҎ্ͷ௨Γ, ‫ݱ‬ঢ়ͷεέδϡʔϧ͸ඇৗʹλΠτͰ, Ұ‫ݱ࣮ݟ‬ෆՄೳͷΑ͏ʹ΋ࢥΘΕΔɻ͔͠͠, ඈ੻‫ݕ‬ग़‫ث‬, Χϩ

5.4

౔໦޻ࣄ

FASER ࣮‫ݧ‬Λ‫ࡏݱ‬༧ఆ͞Ε͍ͯΔ৔ॴͰߦ͏ͨΊʹ͸, ౔໦޻ࣄ͕ඞཁͰ͋ΔɻϏʔϜিಥ࣠ʹରͯ͠,FASER ࣮‫ݧ‬ͷ৔ॴ͸܏͍͍ͯΔɻΑΓଟ͘ͷ৴߸ࣄ৅Ϧϝʔλ, γϯνϨʔλ‫ݕ‬ग़‫ث‬͸, ΫϨʔϯ࡞‫͕ۀ‬ඞཁͳ͍ɻͦͷͨΊ, ΋͠։ൃ͕஗Εͨ৔߹ʹ͸, 2021 ೥ 5݄Ҏ߱ʹ࣮‫ݧ‬৔ॴʹઃஔ͢Δ͜ͱ΋ՄೳͰ͋Δɻ͜͜Ͱ΋, FASER ‫ݕ‬ग़‫͕ث‬ίϯύΫτͰ͋Δͱ͍͏ར఺͕‫׆‬
͖ͯ͘Δɻ

9
81

৽ཻࢠ୳ࡧҎ֎ʹ΋, FASER ‫ݕ‬ग़‫ث‬ͷखલʹΤϚϧγϣϯͱγϦίϯɾετϦοϓΛ༻͍ͨඈ੻‫ݕ‬ग़‫ث‬Λઃʹ, ‫ؾͣͤإͳݏ‬௕ʹ͓෇͖߹͍͍͖ͯͨͩ͠·ͨ͠ɻҎ্ͷΈͳ͞·, େม͋Γ͕ͱ͏͍͟͝·ͨ͠ɻஔ͠, TeV ෇ۙͷχϡʔτϦϊࣄ৅Λଌఆ͢Δͱ͍͏ϓϩδΣΫτ (FASERν) ͕ਐߦதͰ͋Δ [19]ɻFASERν
࣮‫Ͱݧ‬ଌఆͰ͖ΔχϡʔτϦϊͷΤωϧΪʔྖҬ͸, Ճ଎‫ ͱݧ࣮ث‬IceCube ͰଌఆͰ͖ΔΤωϧΪʔྖҬͷஸ౓தؒʹҐஔ͠, ͜Ε·Ͱଌఆ݁Ռ͕ͳ͍ɻ͞Βʹ, ΤϚϧγϣϯΛ༻͍Δ͜ͱͰ, ిࢠχϡʔτϦϊͱϛϡʔχϡʔτϦϊ͚ͩͰͳ͘, λ΢χϡʔτϦϊ·ͰଌఆͰ͖Δɻ‫ࡏݱ‬, CERN ʹఏҊதͰ, ૣ͚Ε͹ FASER ࣮‫ݧ‬ͷ࢝·Δ 2021 ೥͔ΒͷσʔλऔಘΛ໨ࢦ͍ͯ͠Δɻ͜
ͷϓϩδΣΫτ͸‫۝‬भେֶ, ໊‫ݹ‬԰େֶ, ϕϧϯେֶͷํʑ͕த৺ͱͳͬͯ४උ͕ਐΜͰ͓Γ, ࠓ‫ޙ‬ͷਐలʹ‫ظ‬
଴͍ͨ͠ɻ

7

࠷‫ʹޙ‬
2019 ೥ 1 ݄ͷஈ֊Ͱ, FASER ࣮‫ݧ‬͸ LHC ࣮‫ͯ͠ͱݧ‬ࢀߟจ‫ݙ‬[1] M. Battaglieri et al., arXiv: 1707.04591.
[2] A. Ariga et al., arXiv: 1811.10243.
[3] A. Ariga et al., arXiv: 1811.12522.
[4] Y. Hochberg et al., Phys. Rev. Lett. 113 171301(2014).
[5] J. L. Feng et al., Phys. Rev. Lett. 91 011302(2003).
[6] Sean Tulin and Hai-Bo Yu, arXiv: 1705.02358.
[7] J. L. Feng et al., Phys. Rev. D 97 no. 3, 035001(2018).

ೝΊΒΕ͓ͯΒͣ, Heising-Simons ࡒஂͱ Simons ࡒஂ͔Βͷ༧ࢉิॿ΋֬ఆ͍ͯ͠ͳ͔ͬͨɻ͞Βʹ, ATLASSCT ͱ LHCb ి࣓ΧϩϦϝʔλͷεϖΞɾϞδϡʔϧʹ͍ͭͯ΋, FASER ࣮‫΁ݧ‬ఏ‫͢ڙ‬Δͱ͍͏ܾఆ͸ग़͍ͯͳ͔ͬͨɻ·͞ʹͲΕ͕ବ໨Ͱ΋ϓϩδΣΫτ͕ഁ୼
͢Δͱ͍͏ঢ়‫ͨͬͩگ‬ɻ͠͹Β͘ߝ౉ΓͷΑ͏ͳঢ়ଶ͕
ଓ͍͕ͨ, ͻͱ·࣮ͣ‫ݧ‬ͷ‫ݐ‬ઃ։࢝ʹ૨͚͗ͭͨ͜ͱ͸
޾͍Ͱ͋Δɻ·͞ʹ FASER ϛϥΫϧͰ͋Δɻ͔͠͠,ࠓ‫ޙ‬΋෺ཧσʔλͷऔಘ·Ͱ͸೾ཚͳ͜ͱ͕ଓ͘ʹҧ͍ͳ͍ɻ

FASER ࣮‫ݧ‬͸ϓϩδΣΫτͷൃ଍͔Β, ৭ʑͳ͜ͱ͕
‫ٸ‬ϐονͰਐΈ, ࣮‫ݧ‬ͷ্ཱͪ͛ʹؔΘΔશͯͷεςοϓΛ໨ͷ౰ͨΓʹ͢Δ‫و‬ॏͳ‫ػ‬ձΛಘΔ͜ͱ͕Ͱ͖ͨɻ͜Ε͸, ·ͩए͍զʑʹͱͬͯ͸ඇৗʹษ‫ͨͬͳʹڧ‬ɻ͞Βʹ, ‫ࡏݱ‬͸͍͢͝੎͍Ͱ‫ݕ‬ग़‫ث‬ͷ։ൃ͕ਐΜͰ͓Γ, ౰ॳ͸൒৴൒͕ٙͩͬͨ, ຊ౰ʹ 2020 ೥ 5 ݄·Ͱʹશͯͷ։ൃΛ‫͋Ͱ͏͍ͦ·ͯྃ͠͠׬‬Δɻզʑࣗ਎΋, FASER
࣮‫ݧ‬ͷߦ͘຤ָ͕͠ΈͰ͋Δɻ

8ँࣙւ໺ٛ৴͞ΜʢKEKʣʹ͸, ATLAS SCT ͷόϨϧɾϞδϡʔϧΛ։ൃͨ͠‫͖ͮجʹݧܦ‬, ϑϨΩγϒϧ‫ج‬൘ͷઃ‫ݴॿ͝ʹܭ‬Λ͍͖ͨͩ·ͨ͠ɻ௡ଜߒೋ͞Μʢ‫۝‬େʣ, ӬాՆւ͞Μʢ౦େʣ, നҪஐ͞Μʢ౦େ IPMUʣʹ͸, ҉ࠇ෺࣭ͱ͍ܰ৽ཻࢠͷ෺ཧతؔ࿈ʹ͍ͭͯ, ࠙੾ஸೡʹ͝‫ڭ‬त͍͖ͨͩ·ͨ͠ɻϋϠγϨϐοΫ‫ࣜג‬ձࣾͷ੨໦‫͞ݫ‬Μͱੴ௩༤ೋ͞Μʹ͸, ϑϨΩγϒϧ‫ج‬൘ͱύονύωϧͳͲ, ֤छ‫ج‬൘ͷઃ‫ͱܭ‬੡଄Λґཔ͠·ͨ͠ɻզʑͷ౓ॏͳΔઃ‫ܭ‬ͷमਖ਼ґཔͱ‫ج‬൘ͷ࡞Γ௚͠

[8] J. L. Feng et al., Phys. Rev. D 98 no. 5, 055021(2018).
[9] J. L. Feng et al., Phys. Rev. D 97 no. 5, 055034(2018).
[10] F. Kling and S. Trojanowski, Phys. Rev. D 97
no. 9, 095016 (2018).
[11] S. Alekhin et al., Rept. Prog. Phys. 79, 124201(2016), arXiv: 1504.04855.
[12] A. Berlin et al., Phys. Rev. D 98 no. 3, 035011(2016), arXiv: 1804.00661.
[13] The NA62 collaboration, JHEP05 (2019) 182,
arXiv: 1903.08767.
[14] M. Bauer et al., arXiv:1803.05466.
[15] ߴྗ޹, ߴΤωϧΪʔχϡʔε 26-4, 314 (2008).
[16] Speciﬁcation document on ABCD3T ASIC,
http://scipp.ucsc.edu/groups/atlas/elect-doc/abcd3t_spec.pdf.
[17] F. Keizer et al., JINST 13 no. 10, P10028 (2018),
arXiv: 1810.12174.
[18] LHCb Collaboration, LHCb calorimeters : Technical Design Report, http://cds.cern.ch/record/494264.
[19] H. Abreu et al., arXiv: 1908.02310.