dE/dX measurement by OPERA film Tsutomu Fukuda (Nagoya Univ) Emulsion work shop (11/12,2005)

Contents ・ Test exp set up ・ Horizontal sample result ・ Vertical sample preliminary result ・ Conclusion & Future work

Test exp for dE/dx study （ Proton T1 ） dE/dX (MeV g -1 cm 2 ) Momentum(GeV/c) P K μ π Proton beam was used. Pion is exposed with proton at this beam line. dE/dX of proton change slowly. dE/dX was calculated by Bethe-Bloch Equation. dE/dX = K ･ (Z/A) ･ (z 2 /β 2 ) ･ L(β) L(β) = (1/2) ･ (ln((2m e c 2 β 2 γ 2 W m )/I))-β 2 -(C/Z)-(δ/2) Material used on calculation is OPERA emulsion. composition of OPERA emulsion Z A % by weight I Ag Br I C N O H S Si Na Sr Ba K

Test exp for dE/dx study （ Proton T1 ） dE/dX Proton momentum ~ 1.9 → ~1140MeV/c ~ 2.3 → ~870MeV/c ~ 2.7 → ~740MeV/c ~ 3.5 → ~600MeV/c ~ 4.4 → ~500MeV/c ~ 6.0 → ~400MeV/c dE/dX ~ 1.5 → MIP ( ~400MeV/c π) dE/dX (MeV g -1 cm 2 ) Momentum(GeV/c) P K μ π MIP1.5

Sample1 (horizontal sample) ・ for Grain Count ( 600MeV/c P, π ＋ is reference ) 400MeV/c P, π ＋ 600MeV/c P, π ＋ 740MeV/c P, π ＋ 600MeV/c P, π ＋ 870MeV/c P, π ＋ 600MeV/c P, π ＋ 1140MeV/c P, π ＋ 600MeV/c P, π ＋ Sample films is same batch and same refresh and same developing. A B CD

Grain Count by Manual Microscope 45μm eyepiece micrometer ×100 objective lens was used. The thickness of emulsion layer of OPERA film is ~ 45μm. So, counted grains each 45μm by eyepiece micrometer. The aim of this measurement is Check for relation between Grain Density and dE/dX in OPERA film. ※ Grain Density is the number of grain per 100μm.

Uniformity of sensitivity in depth of film Base 205μm Emulsion layer 21μm Protection coat 1μm ・・・・・・ Emulsion layer of OPERA film is coated 2times. So,check uniformity of sensitivity between up layer and down layer for sample films by comparing G.D of up layer and down layer by a same track. ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ G.D of up layer G.D of down layer Side view

Uniformity of sensitivity in depth of film result 400MeV/c film : 400MeV/c π G.D of up layer = 35.3±1.3 G.D of down layer = 35.6± MeV/c film : 740MeV/c π G.D of up layer = 37.1±1.8 G.D of down layer = 34.9± MeV/c film : 870MeV/c p G.D of up layer = 57.6±1.3 G.D of down layer = 57.1± MeV/c film : 1140MeV/c π G.D of up layer = 34.7±1.1 G.D of down layer = 35.1± MeV/c film : 1140MeV/c p G.D of up layer = 45.3±1.1 G.D of down layer = 45.8±1.3 A B C D D Sensitivity between up layer and down layer in each sample film is same within a few % error.

Calibration film by film Measured G.D of 600MeV/c π in each sample film. Length of sample track is more than 900μm. Each G.D is calculated by using 5 tracks. 400MeV/c film : 600MeV/c π G.D = 35.8± MeV/c film : 600MeV/c π G.D = 34.9± MeV/c film : 600MeV/c π G.D = 35.9± MeV/c film : 600MeV/c π G.D = 34.9±0.7 result P, π ＋ 600MeV/c P, π ＋ A B C D Calibration of G.D in sample films uses center of value of G.D of each 600MeV/c π.

Grain Density Result 400MeV/c π G.D = 36.4± MeV/c π G.D = 35.8± MeV/c π G.D = 36.1± MeV/c π G.D = 36.4± MeV/c p G.D = 80.1± MeV/c p G.D = 64.1± MeV/c p G.D = 57.2± MeV/c p G.D = 47.5±0.7 Typically total length of measurement is ~9mm and total number of tracks is ~7 tracks. G.D was calibrated by 600MeV/c πof 400MeV/c film. Error is about size of symbol. G.D = 242 dE/dX =10.0 dE/dX (MeV g -1 cm 2 ) Momentum(GeV/c) G.D P π

dE/dX - Grain Density dE/dX (MeV g -1 cm 2 ) Ｇ．Ｄ ● :proton ● :pion Reference UVSOL e : G.D = 37.9 Grain Density is proportional to dE/dX. But not exactly proportional. Error is about size of symbol, only statistical error. I will estimate systematic error.

Other momentum 600MeV/c p mean 36.2 RMS MeV/c π mean 15.9 RMS MeV/c π mean 15.9 RMS MeV/c π mean 16.2 (870MeV/c film) RMS 3.6 Fluctuation of the number of grains in 45μm 400MeV/c π 1140MeV/c p 870MeV/c p 740MeV/c p mean 16.4/45μm RMS 3.7 χ 2 /ndf = 4.0/7 mean 20.8/45μm RMS 4.1 χ 2 /ndf = 5.8/7 mean 25.9/45μm RMS 4.2 χ 2 /ndf = 6.9/8 mean 28.1/45μm RMS 4.3 χ 2 /ndf = 8.1/9 Distribution of number of grains is not Poisson distribution. RMS ~ sqrt(Mean) Fitting by Binomial Distribution, It is good fitting.

Next step : Analysis of distribution of the number of grains in 45μm ・ r AgBr Distribution of size of AgBr in OPERA emulsion by electron micrograph Mean = 201 nm Sigma = 18 nm The average number of AgBr per 45μm is ~105 grains in view of crystal size and volume concentration. Probability of developing ∝ fun(path length in crystal(r)). It can be estimated by analyzing shape of distribution. I will try about this. Volume concentration of AgBr is 31%

Sample 2 (vertical sample) ・・・ P, π ＋ beam OPERA film 30 plates 400MeV/c 500MeV/c 600MeV/c 2 GeV/c (4 angle exposed ~0.0, 0.1, 0.3, 0.5 rad) ・ for VPH measurement by UTS Density~10 3 /cm 2 /angle/momentum ・・・ P, π ＋ beam 740MeV/c 870MeV/c 1140MeV/c 2 GeV/c Density~10 3 /cm 2 /angle/momentum pl01 angle distribution of base track 400MeV/c 600MeV/c 500MeV/c 2.0GeV/c 1140MeV/c 740MeV/c 870MeV/c 2.0GeV/c CS (4 angle exposed ~0.0, 0.1, 0.3, 0.5 rad) (rad)

VPH measurement Result for ~0.0rad tracks D D D ※ D is Deuteron 0.6 GeV/c2.0 GeV/c 0.74 GeV/c0.87 GeV/c1.14 GeV/c2.0 GeV/c P P P P π π π π D D P&π Entry 637 tracksEntry 1063 tracksEntry 979 tracks Entry 898 tracks Entry 677 tracksEntry 1219 tracks 0.4 GeV/c Entry 511 tracks P π 0.5 GeV/c Entry 631 tracks π P D (Average VPH of track connected 15 ~ 17 plates) At 2 GeV/c, proton and pion are not separated in 15~17 OPERA films.

VPH - Grain Density VPH = 1285 dE/dX = 10.0 Error is about size of symbol. VPH of proton below 600MeV/c is saturated. Error is about size of symbol. In MIP-740MeV/c Proton region, VPH is proportional to Grain Density. Ｇ．Ｄ ● :proton ● :pion reference UVSOL e : G.D = 37.9 ＶＰＨ dE/dX (MeV g - 1 cm 2 ) Momentum(GeV/c) VPH-dE/dX VPH-G.D P π In MIP-740MeV/c Proton region G.D >100

Conclusion ・ Study of dE/dX measurement for vertical track. ・ Check of uniformity of sensitivity for all OPERA film. between up layer and down layer film by film ・ Study of fading effect. ・ Analysis of distribution of the number of grains in 45μm. ・ Grain Density is proportional to dE/dX, But not exactly proportional. I will estimate systematic error. ・ First data of relation between G.D and VPH is got. Future work

That’s All

Back up

Background Study for OPERA Main Background of ν τ ＣＣ event is charm production event in ν μ ＣＣ event. Charmed particle( D, Λc ) mass is nearly equal τ mass,and their life time is very short. It is very difficult to separate them. → Separate them by μ existence in νinteraction vtx. ID!! ντντ π τ stop ! νμνμ μ D Background event ν τ interaction appearance It is important for μ existence to separate π/μ in νinteraction vtx.

π/μseparation π/μseparation (>1GeV/c) π→ almost (~96%) interact in 10 Bricks. μ→ almost (~100%) pass 10 Bricks. It is easy to separate. π/μseparation (<1GeV/c) → Analysis of dE/dX,Range,Scattering in ECC dE/dX, Range and Scattering study is essential for π/μseparation in low energy region. This time, I talk about dE/dX study.

dE/dX as a function of path length from lost position for muon and pion Track connection is applied using sigma assuming p  <0.01 Red and green dots are of muon and pion. No good  separation at less than 0.5cm from lost point. To get good separation and number of grains, grain density averaged over 1-3cm region (dE/dX : region) are used for ID. π ： green μ ： red Range from lost point(cm)

π/μseparation study π/μ に関して言及

Probability of developing

Connect tracks

Penta quark search & J-PARC & balloon dE/dX study

VPH(Volume Pulse Height) １枚の plate の片面乳剤層での VPH 分布。