ハイブリッドエマルション法を用いたダブルハイ...

日本物理学会第71回年次大会2016.03.21

ハイブリッドエマルション法を用いた

ダブルハイパー核探索実験 (J-PARC E07)

京都大学・JAEA　江川弘行

J-PARC E07 collaboration

ダブルハイパー核バリオン相互作用 SU(3)f 対称性でよく記述されているS = 0,1

- 核子散乱実験- ハイパー核生成実験

S = -2- データはほとんど無い- ハイペロン同士の散乱実験は難しい

• τ : ~10-10s

ダブルハイパー核が S = -2 の重要なプローブ - Λを2つ含む原子核- ΛΛ相互作用の情報が得られる- 連続する弱崩壊をエマルションで捉えるのが有効

• 位置分解能 : < 1μm

ΛΛ

2 CHAPTER 1. INTRODUCTION

S=0 NN(T=1)

27s

10a

10a

8s

8a

1s

S=-1 ΣN(T=3/2) ΣN-ΛN(T=1/2)S=-2 ΣΣ(T=2) ΞN-ΣΛ-ΣΣ(T=1) ΞN-ΣΣ-ΛΛ(T=0)

S=-4 ΞΞ(T=1)

S=0 NN(T=0)S=-1 ΣN-ΛN(T=1/2)S=-2 ΞN-ΣΛ(T=1)S=-3 ΞΣ(T=3/2)

S=-1 ΣN(T=3/2)

S=-3 ΞΣ(T=3/2) ΞΣ-ΞΛ(T=1/2)

S=-2 ΞN-ΣΛ-ΣΣ(T=1)

S=-3 ΞΣ-ΞΛ(T=1/2)S=-4 ΞΞ(T=0)

S=-1 ΣN-ΛN(T=1/2)S=-2 ΞN-ΣΛ(T=1) ΞN-ΣΣ-ΛΛ(T=0)S=-3 ΞΣ-ΞΛ(T=1/2)

S=-1 ΣN-ΛN(T=1/2)

S=-3 ΞΣ-ΞΛ(T=1/2)S=-2 ΞN-ΣΛ-ΣΣ(T=1) ΞN(T=0)

S=-2 ΞN-ΣΣ-ΛΛ(T=0)

Figure 1.1: Irreducible representations for two-baryon system based on SU(3)flavor

.

バリオンの2体系の既約表現 (SU(3)f)

1.1. BARYON-BARYON INTERACTION 3

of the baryon-baryon interaction. Recent progress of the studies on the hyperon-nucleon interactions gives us information of multiplets other than 1s sector, eventhough experimental results are still poor compared to the NN sector. Informa-tion of 1s sector can be obtained only from the studies on doubly strange systems.However, experimental data for S = −2 sector on baryon-baryon interaction isextremely limited so far, as mentioned later.

The observation of double-Λ hypernuclei gives important information aboutthe Λ-Λ interaction. The binding energy of two Λ hyperons, B

ΛΛ

, and the Λ-Λinteraction energy, ∆B

ΛΛ

, can be obtained from the measurement of the massesof double-Λ nuclei, where B

ΛΛ

and ∆BΛΛ

are defined by

BΛΛ

( AΛΛ

Z) = M(A−2Z) + 2M(Λ)−M( AΛΛ

Z) (1.3)

∆BΛΛ

( AΛΛ

Z) = BΛΛ

( AΛΛ

Z)− 2BΛ

(A−1

Λ

Z). (1.4)

Since hyperon-hyperon scattering experiments are extremely difficult, the obser-vation of double-hypernuclei is currently an unique experimental approach toextract the information about the Λ-Λ interaction.

Double-Λ hypernuclei are closely related to the existence of an H dibaryon.The H dibaryon was originally predicted by Jaffe in 1977 [1] as a particle con-stituting six quarks of uuddss with the configuration of color-singlet, SU(3)

flavor

-singlet, and JPC = 0++. The eigenvalue of the Casimir operator C

6

in eq. (1.2)becomes 144 in such a configuration. It gives strongly attractive color-magneticinteraction of ∆ = −24α. Jaffe predicted the mass of the H dibaryon using theMIT bag model to be 2150 MeV/c2, which is smaller than twice the Λ hyperonmass. Since then, many theorists have calculated its mass using various modelsand their results vary from below two nucleons mass to above the two-Λ threshold.The theoretical calculations on the H dibaryon are reviewed in Ref. [2].

If the mass of the H dibaryon, M(H), was less than twice the Λ hyperonmass in a nucleus, two Λ hyperons in the nucleus would be expected to formthe H immediately. With this assumption, the lower limit of the mass of the Hdibaryon can be calculated from the following relation;

M(H) > 2M(Λ)−BΛΛ

, (1.5)

where M(Λ) is the mass of a Λ hyperon in free space. This relation would notbe changed even if an observed double-hypernucleus had been the H nucleus. Ifthe H dibaryon is bound in a nucleus, the binding energy of the H, BH , can bedefined by

BH = M(A−2Z) + M(H)−M(AHZ), (1.6)

where the mass of the H nucleus, M(AHZ), is equal to M( A

ΛΛ

Z) in eq. (1.3). Bycombining eq. (1.3) and eq. (1.6), the H mass can be written as

M(H) = 2M(Λ)−BΛΛ

+ BH

> 2M(Λ)−BΛΛ

,

2

過去の実験 J. K. AHN et al. PHYSICAL REVIEW C 88, 014003 (2013)

TABLE I. Track lengths and emission angles from vertices A, B, and C of the Nagara event. Several values with underline are correctedones for typos in the previous paper [8].

Point Track Length (µm) θ (degree) φ (degree) Comment

A 1 8.1 ± 0.3 44.9 ± 2.0 337.5 ± 1.8 double-# hypernucleus2 3.2 ± 0.4 57.7 ± 5.2 174.9 ± 2.93 88.6 ± 0.5 156.2 ± 0.5 143.0 ± 1.0

B 4 9.1 ± 0.3 77.7 ± 1.6 115.9 ± 0.8 single-# hypernucleus5 82.1 ± 0.6 122.8 ± 1.0 284.2 ± 0.7 stopped in base6 13697 81.0 ± 0.5 305.5 ± 0.2 π−

C 7 742.6 ± 0.6 138.5 ± 0.2 322.1 ± 0.3 stopped in D-Block8 5868 ± 20 52.2 ± 1.2 123.7 ± 0.7 scattered before stopping

given to be 5.68 MeV by Nakamura et al. [20]. Althoughwe took 7.0 MeV as its upper limit in the previous paper,interpretation of the event is not influenced by the new valueof the 7

#He binding energy.We found again that the case of a #

6#He is consistent in

both processes of production and decay as follows:

12C + %− → #6#He + 4He + t

↪→ 5#He + p + π−.

Kinematic fitting has been performed for the vertices A andB; the values of B## and 'B## were obtained as a functionof the %− binding energy (B%− ):

B## = 6.79 + 0.91 B%− (±0.16) MeV,

'B## = 0.55 + 0.91 B%− (±0.17) MeV.

Taking into account a B%− of 0.13 MeV [21] for the 12C-%−

system, the values of B## and 'B## are 6.91 ± 0.16 MeVand 0.67 ± 0.17 MeV, respectively.

TABLE II. Possible production modes of the double-# hypernu-cleus, the Nagara event. Although the vertex is also coplanar withinerror, the cases of neutron emission are presented. Only the cases of'B## − B%− < 20 MeV are listed. In case (1), values by kinematicfitting for the vertices A and B are presented in the text.

Target 1 2 3 B## − B%− 'B## − B%−

[MeV] [MeV]

12C #6#He 4He p 2n >16.46 >10.22

12C #6#He 4He d 1n 14.08 ± 0.63 7.84 ± 0.63

12C #6#He 4He t 6.93 ± 0.19 0.69 ± 0.20 (1)

12C #7#He 4He p 1n 21.24 ± 1.24 12.88 ± 1.26

14N #6#He 7Li p 1n 24.02 ± 1.98 17.78 ± 1.98

14N #6#He 6Li d 1n 25.42 ± 1.25 19.18 ± 1.25

14N #6#He 4He 4He 1n 17.55 ± 1.47 11.31 ± 1.47

14N #7#Li 4He t 1n 25.79 ± 0.87 16.79 ± 0.87

14N #8#Li 4He d 1n 31.16 ± 1.50 20.00 ± 1.50

14N #9#Li p 4He 1n 31.06 ± 1.33 17.46 ± 1.33

16O #8#Li 4He 4He 1n 30.66 ± 0.83 19.50 ± 0.83

B. “Mikage” event

The event was tagged by a K+ meson of which mo-mentum and mass were measured to be 1.105 GeV/c and0.493 GeV/c2, respectively. Figure 3 shows a photographand schematic drawing of production and decay of a double-hypernucleus for the Mikage event. A %− hyperon came to restat point A, from which two charged particles (tracks 1, 2) wereemitted. One of them (1) decayed into two charged particles(3, 4) at point B. The particle of track 3 decayed again to twocharged particles (5, 6) at point C. The particle of track 6 wasescaping from the emulsion stack to the upstream Scifi-Blockdetector (U-Block). The coplanarity calculated from anglesof tracks 3, 5, and 6 was −0.35 ± 0.13, so the three tracksare coplanar within three standard deviations. The lengths andangles of these tracks are summarized in Table III.

The particle of track 4 stopped in the emulsion afternearly 20 mm flight from the decay point (B) of a doublehypernucleus. There are no charged particles emitted from itsstopping point. In order to identify the species of the track4, we performed the energy-loss measurement (counting ofdeveloped grain per unit length of emulsion, “grain density”)at four regions within 10 mm from point B. If we assume theparticle of the track and its initial kinetic energy, the graindensity can be calculated for each region along the track.Therefore, by minimizing the sum of the deviation betweenthe measured grain density and calculated one at each regionin the emulsion stack, we obtained the initial kinetic energyand the goodness of the fitting (χ2) for each assumed species.Meanwhile, the kinetic energy was also derived from therange-energy relation, which is independent of the energy-lossmeasurement. These results are presented in Table IV, and thusthe particle of track 4 was found to be a proton by comparisonof both data.

10µm

10 µm

#6#5#3

#2

#1C

BA

Ξ-#4

FIG. 3. Photograph and schematic drawing of the Mikage event.

014003-4

J. K. AHN et al. PHYSICAL REVIEW C 88, 014003 (2013)

TABLE I. Track lengths and emission angles from vertices A, B, and C of the Nagara event. Several values with underline are correctedones for typos in the previous paper [8].

Point Track Length (µm) θ (degree) φ (degree) Comment

A 1 8.1 ± 0.3 44.9 ± 2.0 337.5 ± 1.8 double-# hypernucleus2 3.2 ± 0.4 57.7 ± 5.2 174.9 ± 2.93 88.6 ± 0.5 156.2 ± 0.5 143.0 ± 1.0

B 4 9.1 ± 0.3 77.7 ± 1.6 115.9 ± 0.8 single-# hypernucleus5 82.1 ± 0.6 122.8 ± 1.0 284.2 ± 0.7 stopped in base6 13697 81.0 ± 0.5 305.5 ± 0.2 π−

C 7 742.6 ± 0.6 138.5 ± 0.2 322.1 ± 0.3 stopped in D-Block8 5868 ± 20 52.2 ± 1.2 123.7 ± 0.7 scattered before stopping

given to be 5.68 MeV by Nakamura et al. [20]. Althoughwe took 7.0 MeV as its upper limit in the previous paper,interpretation of the event is not influenced by the new valueof the 7

#He binding energy.We found again that the case of a #

6#He is consistent in

both processes of production and decay as follows:

12C + %− → #6#He + 4He + t

↪→ 5#He + p + π−.

Kinematic fitting has been performed for the vertices A andB; the values of B## and 'B## were obtained as a functionof the %− binding energy (B%− ):

B## = 6.79 + 0.91 B%− (±0.16) MeV,

'B## = 0.55 + 0.91 B%− (±0.17) MeV.

Taking into account a B%− of 0.13 MeV [21] for the 12C-%−

system, the values of B## and 'B## are 6.91 ± 0.16 MeVand 0.67 ± 0.17 MeV, respectively.

TABLE II. Possible production modes of the double-# hypernu-cleus, the Nagara event. Although the vertex is also coplanar withinerror, the cases of neutron emission are presented. Only the cases of'B## − B%− < 20 MeV are listed. In case (1), values by kinematicfitting for the vertices A and B are presented in the text.

Target 1 2 3 B## − B%− 'B## − B%−

[MeV] [MeV]

12C #6#He 4He p 2n >16.46 >10.22

12C #6#He 4He d 1n 14.08 ± 0.63 7.84 ± 0.63

12C #6#He 4He t 6.93 ± 0.19 0.69 ± 0.20 (1)

12C #7#He 4He p 1n 21.24 ± 1.24 12.88 ± 1.26

14N #6#He 7Li p 1n 24.02 ± 1.98 17.78 ± 1.98

14N #6#He 6Li d 1n 25.42 ± 1.25 19.18 ± 1.25

14N #6#He 4He 4He 1n 17.55 ± 1.47 11.31 ± 1.47

14N #7#Li 4He t 1n 25.79 ± 0.87 16.79 ± 0.87

14N #8#Li 4He d 1n 31.16 ± 1.50 20.00 ± 1.50

14N #9#Li p 4He 1n 31.06 ± 1.33 17.46 ± 1.33

16O #8#Li 4He 4He 1n 30.66 ± 0.83 19.50 ± 0.83

B. “Mikage” event

The event was tagged by a K+ meson of which mo-mentum and mass were measured to be 1.105 GeV/c and0.493 GeV/c2, respectively. Figure 3 shows a photographand schematic drawing of production and decay of a double-hypernucleus for the Mikage event. A %− hyperon came to restat point A, from which two charged particles (tracks 1, 2) wereemitted. One of them (1) decayed into two charged particles(3, 4) at point B. The particle of track 3 decayed again to twocharged particles (5, 6) at point C. The particle of track 6 wasescaping from the emulsion stack to the upstream Scifi-Blockdetector (U-Block). The coplanarity calculated from anglesof tracks 3, 5, and 6 was −0.35 ± 0.13, so the three tracksare coplanar within three standard deviations. The lengths andangles of these tracks are summarized in Table III.

The particle of track 4 stopped in the emulsion afternearly 20 mm flight from the decay point (B) of a doublehypernucleus. There are no charged particles emitted from itsstopping point. In order to identify the species of the track4, we performed the energy-loss measurement (counting ofdeveloped grain per unit length of emulsion, “grain density”)at four regions within 10 mm from point B. If we assume theparticle of the track and its initial kinetic energy, the graindensity can be calculated for each region along the track.Therefore, by minimizing the sum of the deviation betweenthe measured grain density and calculated one at each regionin the emulsion stack, we obtained the initial kinetic energyand the goodness of the fitting (χ2) for each assumed species.Meanwhile, the kinetic energy was also derived from therange-energy relation, which is independent of the energy-lossmeasurement. These results are presented in Table IV, and thusthe particle of track 4 was found to be a proton by comparisonof both data.

10µm

10 µm

#6#5#3

#2

#1C

BA

Ξ-#4

FIG. 3. Photograph and schematic drawing of the Mikage event.

014003-4

弱い引力

BΛΛ = 6.91 ± 0.16 MeVΔBΛΛ = 0.67 ± 0.17 MeV

Ξ- stop ダブルハイパー核

M.Danysz 4 1

KEK E176 80 1

KEK E373 800 7

これまでにもエマルションを用いたダブルハイパー核探索実験は行われている。 NAGARAイベント

核種が同定されたものは6ΛΛHeのみ (KEK E373)Hダイバリオンの質量の下限 : MH > 2223.7 MeV/c2

新たな核種を発見し、ΛΛ相互作用を系統的に調べることが重要である。- ΔBΛΛの原子核依存性- ダブルハイパー核の崩壊分岐比

3

J-PARC E07 実験✤ ダブルハイパー核探索実験✤ ハイブリッドエマルション法✤ E373実験の10倍の統計

- エマルション量 (x2), K-純度 (x4),アクセプタンス(x1.4)

- 100 個のダブルハイパー核- 10 個の核種を同定

✤ Ξ- 原子のX線をGe検出器群で測定

K+Ξ-

diamond target

SSD Emulsion

K-

• ハイブリッドエマルション法

mom [GeV/c]-Ξ

0 0.2 0.4 0.6 0.8 1 1.2 1.40

1000

2000

3000

4000

5000

6000

7000

8000

stopping ratio-Ξ

h1Entries 221028Mean 0.6339RMS 0.1569Integral 2.21e+05

stopping ratio (2b) : 2.41 %

stopping ratio-Ξ

mom [GeV/c]-Ξ

0 0.2 0.4 0.6 0.8 1 1.2 1.40

1000

2000

3000

4000

5000

6000

7000

8000

stopping ratio-Ξ



stopping ratio-Ξ

mom [GeV/c]-Ξ

0 0.2 0.4 0.6 0.8 1 1.2 1.40

1000

2000

3000

4000

5000

6000

7000

8000

stopping ratio-Ξ



stopping ratio-Ξ

検出するΞ-のうち約2%がエマルション中で静止する

- tagged Ξ- - Ξ- stop in emulsion

p

nΛᲫᲨExperimental motivation

Study of hadron-hadron interaction

Stra

ngen

ess s = -∞

[N-Star/Strange Matter]

㻔㻕㻔㻕

NAGARA event

Baryon octet Continuous research of experimental and theoretical for more than 50 years

䞉1�1�LQWHUDFWLRQ䞉<�1�LQWHUDFWLRQ

ZKHUH�<� �(Σ, Λ)

Steadily Progressing

Study of 䞉Λ-Λ interaction䞉Ξ-N interaction

Next subject

The most powerful method for the detection of D.H.N.ń Emulsion experiment !!

Nuclear Chart with Strangeness

Unstable NuclideStable Nuclide

- 2 / 12 -

Ξ-の軌跡を顕微鏡で自動追跡する

4

Simulation

セットアップ

Beam Line Spectrometer

KURAMA SpectrometerEmulsion SSD

Hyperball-X(Ge)

Diamond Target

QQDQmagnets

KURAMA magnetcollimator

K-

K+

Ξ-

J-PARC K1.8 beam linep(K-,K+)Ξ- @1.8 GeV/c

K1.8ビームラインにはSKSスペクトロメータがインストールされており、KURAMAスペクトロメータの検出器を新たに開発する必要がある 5

acceptance : 280 mrad magnetic field : 0.7 T

KURAMA 検出器 ✤ 検出器開発は完了✤ 架台を組み立て中

6

Fabrication of BAC’s

��

BAC PVACFAC

2 August 201418

TRG

144 x 44 x ? mm

3 H1949-50

STR 10 x 10 x 4 m

m3

H3167B

BH1 120 x 40 x 6 m

m3

H10570 BH2 120 x 40 x 6 m

m3

H2431-50

BH2

Hyperball-X SSD CHFBH TOF

SDC3

SDC2

SDC1

エマルション✤記録可能密度 : 104/mm2✤ 350mm[H] x 345mm[W] x 12mm[T] (2枚の薄型 + 11 枚の厚型)✤ 2.1 t のゲルを用いて mass production (2014年 5月に完了)✤ 110 スタック分✤神岡鉱山にて保管✤鉛ブロックで遮蔽✤サンプルを用いて放射線ダメージを　　　　　　　　　　　　　　モニターしている

Emulsion Mover ✤エマルション乾板をspill毎に動かす✤常に位置を記録✤位置分解能 : 数 μm

Status%of%E07%emulsion �1�Mass%produc-on%(1380%thick%and%240%thin%plates)%has%been%�one%from%Dec.,%2013%to%May,%2014.%%=>%~600%days%have%passed%since%the%first%produc-on.�

20th%J<PARC%PAC%mee-ng� ��

Cosmic%ray�

Compton%%electron�

Cosmic%rays� Compton%electron�

Pb%blocks%(t%10cm)�

Our%emulsions%have%been%accumula-ng%background%events%from%cosmic%rays%and%Compton%electrons%!!�

エマルションカセット

7

E07コミッショニングラン (2015 秋)

エマルションムーバー・SSD・AC検出器をK1.8ビームラインにインストールして、コミッショニングランを行った。

ビーム強度・プロファイルチェック : 30h - K- ビーム　　　 : 本ラン用- p̅ ビーム, πビーム : 位置較正用

• 様々なβのビームによるAC検出器の性能評価

エマルション照射 : 24h • SSD-エマルション位置較正- ビームを用いたパターンマッチ

21aAW-5 “J-PARC E07のハイブリッドエマルション法” 吉田純也

8

SSD

カセットホルダー

BAC PVAC FAC

ビームチェック

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

1.8 GeV/c K- ビーム1次ラインの強度 : 39kW要求 - 300k/spill- K/all = 85% (K:π =6:1)

現在のビームパワーで達成ターゲット領域 : 95%

X [mm]-50 -40 -30 -20 -10 0 10 20 30 40 500

1000

2000

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X profile w/o Q13h41

Entries 125302Mean -0.5929RMS 9.457Integral 1.246e+05

X profile w/o Q13

Y [mm]-50 -40 -30 -20 -10 0 10 20 30 40 500

1000

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Y profile w/o Q13

0

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m]

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-10

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Entries 125302Mean x -0.595Mean y -1.935RMS x 9.396RMS y 6.437Integral 1.243e+05

Y:X profile w/o Q13

X [mm]-50 -40 -30 -20 -10 0 10 20 30 40 500

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X profile w/ Q13

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Entries 125849Mean 1.361RMS 4.285Integral 1.254e+05

Y profile w/ Q13

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m]

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Entries 125849Mean x -2.762Mean y 1.391RMS x 15.16RMS y 4.14Integral 1.244e+05

Y:X profile w/ Q13

target50 mm x 30 mm

K- inte

nsity

[/s

pill (

5.5s

cyc

le)]

K- purity

9

ターゲット位置でのビームプロファイル

ビーム強度とK-純度の関係

AC性能評価

E07実験に十分な性能10

p

n/

Performance of AC detector

n=1.03n=1.05

n=1.16

β 1

0.95

0.9

0.85

0.8

0.75

0.70.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 [GeV/c]

All AC detectors show good performance for E07.

n=1.03 n=1.05 n=1.16

1.67 GeV/c pion >99%

0.9 GeV/c Kaon ~1% ~3% >99%

0.9 GeV/c proton ~1% ~3%

2313 /

p

n/

Performance of AC detector

n=1.03n=1.05

n=1.16

β 1

0.95

0.9

0.85

0.8

0.75

0.70.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 [GeV/c]

All AC detectors show good performance for E07.

n=1.03 n=1.05 n=1.16

1.67 GeV/c pion >99%

0.9 GeV/c Kaon ~1% ~3% >99%

0.9 GeV/c proton ~1% ~3%

2313 /

BACFAC

PVAC

散乱πビームK

ビームπのVETO

散乱p (低運動量) のVETO

のVETO

SKS→KURAMA

11

SKSスペクトロメータの解体・撤去KURAMA磁石の設置・検出器用ケガキ

2015年11月

K1.8エリア

が完了

現在

まとめと今後の予定✤ E07実験では、エマルションとスペクトロメータの解析を組み合わせることで効率よく多数のダブルハイパー核を探索する

✤ K-ビームの確認、検出器の開発は完了

✤ KURAMAスペクトロメータのインストールが現在進行中

✤ 2016年5,6月にKURAMAスペクトロメータを立ち上げ、20スタック分のデータを取得する- KEK E373実験の2倍の統計量

✤ 2017年に全エマルションの照射が完了

12

backup

13

KURAMAスペクトロメータ　検出器

Fabrication of BAC’s

��

K+

K-

KURAMA spectrometer

acceptance : 280 msr

2 August 2014 18

TRG 144 x 44 x ? mm3 H1949-50

STR 10 x 10 x 4 mm3

H3167B

BH1 120 x 40 x 6 mm3

H10570 BH2 120 x 40 x 6 mm3 H2431-50

BAC

PVACFAC

BH2

KURAMA magnet

TOF

Timing counters • BH2 : ⊿t 80 ns (σ) • TOF : ⊿t 90 ns (σ)

400 600 800 1000 1200 1400 1600 1800 20000.7

0.75

0.8

0.85

0.9

0.95

1

beta

momentum [MeV/c]

β thresholdn=1.03n=1.05

n=1.16pK

π

Aerogel Cherenkov counters • BAC : index 1.03

(Beam AC) • PVAC : index 1.16

(Proton Veto AC) • FAC : index : 1.05

(Forward AC)

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KURAMAスペクトロメータ　検出器

Matrix Trigger✤ TOF : 24 segments

(Time Of Flight)✤ CH : 64 segments

(Charge Hodoscope)✤ FBH : 16 segments

(Fine Beam Hodoscope)

Drift Chambers✤ DC1 : 6 layers (XUVX’U’V’)✤ DC2 : 4 layers (XYX’Y’)✤ DC3 : 4 layers (XYX’Y’)

K+

K-

TOF

CH

FBH

DC3DC2

DC115

セットアップ (2015秋)

16

KUAC

BH2-2

CH

SAC・FAC・PVAC

SSD1,2・Emulsion

BAC1,2

BH2

SSD0

Q13SKS

Emulsion cassette holder

SSDBeam

1.67 → 1.8 GeV/c元々はΞ- stopの割合が最適となる1.67 GeV/cでE07実験を行う予定だった。

✤ p(K-,K+)Ξ-の収量- Y1.8 / Y1.67 = ~1.3 (E05パイロット)

✤ Ξ- stop の割合- P1.8 / P1.67 = 0.9

1.8 GeV/c の方がダブルハイパー核の収量が多くなる

✤ ビーム強度- I1.8 / I1.67 = 1.5

170

50000

100000

150000

200000

250000

300000

350000

400000

450000

0 2 4 6 8 10 12 14 16 18

��1

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

0 2 4 6 8 10 12 14 16 18

��1

1.8 GeV/c 1.67 GeV/c

K/π K/π

K-/spill K-/spill

トリガーレート✤ JAMで発生させたイベントを元に、Geant4でシミュレーションを行った。✤ ACの検出効率はしきい値を超えたものについて100%としている。✤ DAQ eff. を90% にするにはトリガーレートを <1000/spill に抑える必要がある。

18

トリガーレート [/spill]ACのみ 3600

AC+2DMT 1660AC+3DMT 1120

AC+3DMT+MsT 540

発生条件K- : 300k/spill

2DMT (Matrix Trigger)CH・TOFのヒットパターン

3DMT (Matrix Trigger)FBH・CH・TOFのヒットパターン

MsT (Mass Trigger)CH・TOFのヒットパターンと飛行時間

3DMTとMsTを導入することでトリガーレートを<1000/spillに抑えられる。

トリガーレート vs DAQ eff.

19

Estimation of DAQ Efficiency•DAQ Efficiency vs Trigger request

- by using some combinations of coincidences during the E05 beam time

6

DAQ Eff.

40%

50%

60%

70%

80%

90%

100%

request [/spill]0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

100us 150us 200us 250us

if we want to achieve DAQ efficiency of 90%, we have to reduce the trigger request to

less than 1000/spill.



6

DAQ Eff.

40%

50%

60%

70%

80%

90%

100%

request [/spill]0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

100us 150us 200us 250us





6

DAQ Eff.

40%

50%

60%

70%

80%

90%

100%

request [/spill]0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

100us 150us 200us 250us





6

DAQ Eff.

40%

50%

60%

70%

80%

90%

100%

request [/spill]0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

100us 150us 200us 250us





6

DAQ Eff.

40%

50%

60%

70%

80%

90%

100%

request [/spill]0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

100us 150us 200us 250us





6

DAQ Eff.

40%

50%

60%

70%

80%

90%

100%

request [/spill]0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

100us 150us 200us 250us



DAQ busy

K1.8ビームラインのビーム構造 (duty : 40%) を加味したトリガーレートとDAQ eff. の関係

理研実験

20

❖ エマルション中の飛跡の太さから粒子の識別する❖ 1H, 2H, 3H, 3He, 4He, 7Li, 9Be, 11B ビームを使用

Beam

エマルション

ビーム計測用カウンター

p

n/

Identification of decay daughterson NP1406-RRC32-02@RIKEN

Range from stopping point [Pm]20 30 40 50 60 70 80 90 100

2.5

2.0

1.5

1.0

0.5

Volume ratio to reference 1H (Average)■：11B ■：4He■：9Be ■： 1H■：7Li

1H

Very Preliminary

4He

7Li

9Be

11B

Although development of analysis around short range is quite necessary,it seems to be separated around 80 ~100 Pm in three standard deviations.

Track image around stops in Em.

Ar

Ne

O

N

C

H.H.Heckman et al., Phys. Rev. 117 (1960) p.544

2321 /

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ハイブリッドエマルション法を用いた ダブルハイ...

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ハイブリッドエマルション法を用いたダブルハイ...