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Search for QFS anomaly in pd - breakup reaction below E p = 19 MeV

Search for QFS anomaly in pd - breakup reaction below E p = 19 MeV. Shuntaro Kimura, K. Sagara, S. Kuroita, T. Yabe, M. Okamoto, K. Ishibashi, T. Tamura, S. Tanaka, Y. Maeda 1 , Y. Ooishi 2 , Y. Ishibashi 2 , A. Ozawa 2 , Y. Tagishi 2 and T. Komatsubara 2

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Search for QFS anomaly in pd - breakup reaction below E p = 19 MeV

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  1. Search for QFS anomalyin pd-breakup reaction below Ep=19 MeV Shuntaro Kimura, K. Sagara, S. Kuroita, T. Yabe, M. Okamoto, K. Ishibashi, T. Tamura, S. Tanaka, Y. Maeda1, Y. Ooishi2, Y. Ishibashi2, A. Ozawa2, Y. Tagishi2 and T. Komatsubara2 Department of Physics, Kyushu University, 1 Department of Applied Physics, University of Miyazaki, 2 Department of Physics, University of Tsukuba

  2. Anomalies in N+d (p+d & n+d) reactions • Low energy region below about 30 MeV • Ay • s • s reaction Anomaly #1. Space Star anomaly (s) #2. Quasi-Free Scattering anomaly (s) < APFB2011 >

  3. #1. Space Star anomaly (review) • Low energy region in pd-breakup reaction • Space Star anomaly is well-known. ● TUNL (1996) 13 MeV Space Star configurationin pd-breakup reaction ○ Erlangen (1989) ■ KUTL (2002) nd exp. > nd calc. □ Koeln (1991) +30% a=90° pd exp. < pd calc. -15% c.m. system Space Star Calc. by A. Deltuva et al. (2005) < APFB2011 >

  4. #1. Space Star anomaly (review) • a-dependence of Star cross section a= 90° 13 MeV Space Star s (exp.) / s (calc.) Anomaly appears around a= 90° Energy dependence of SS anomaly ○ Erlangen (89’, 93’) △ TUNL (96’, 01’, 05’) ◇ Bochum (1989) ○ Koeln (91’, 96’) a [deg] ― CDB SS anomaly in pd-breakup was confirmed. Origin of SS anomaly is not known. < APFB2011 >

  5. #2. Quasi-Free Scattering (QFS) anomaly • Low energy region in pd-breakup reaction • QFS anomaly has been also reported from some experiments. pp-QFS nn-QFS Lab system Lab system 19 MeV 26 MeV 2002 @ Bonn 1996 @ Koeln < APFB2011 >

  6. #2. Energy dependence of QFS anomaly • Energy dependence of QFS cross section • QFS anomaly has similarities with SS anomaly. • Anomalies in cross section • Charge asymmetry • Origin of QFS anomaly is also not known. nd exp. > nd calc. s (exp.) / s (calc.) □ CIAE (2007) ○ Bonn (2002) □ Koeln (72’, 91’, 96’) pd exp. < pd calc. ○ Grenoble (1972) Energy [MeV] < APFB2011 >

  7. Motivation • This time, we measured pp-QFS cross sections. • Reasons (We chose pp-QFS) • E-dependence has not been established. • Experimental precision (pd > nd ) • Reliable pd calculation by A. Deltuva et al (2005) becomes available. • Our strategy ① Systematic and precise experiments on pp-QFS cross section. ② Compare the data with the reliable pd calculation. ③ Confirm whether pp-QFS anomaly is true or not. nn-QFS pp-QFS < APFB2011 >

  8. [Ⅰ] Previous experiments @ KUTL • We measured pp-QFS cross sections at 9.5 & 13 MeV. • Contrary to Koeln group that used a polarized beam, we used an unpolarized proton beam in tandem accelerator lab (KUTL). • In order to measure ONLY cross section. 13 pp-QFS 9.5 Lab system < APFB2011 >

  9. [Ⅰ] Previous experimental results • 9.5 & 13 MeV pp-QFS cross sections (at q1= q2) Result at 9.5 MeV Result at 13 MeV QFS QFS < APFB2011 >

  10. [Ⅰ] Previous experimental results • Energy dependence of QFS cross section 13 q1= q2 □ CIAE (2007) 9.5 ○ Bonn (2002) s (exp.) / s (calc.) □ Koeln (72’, 91’, 96’) Next ○ Grenoble (1972) ● KUTL (2009) Additional experiments Change the detection angle Energy [MeV] q1＜ q2 < APFB2011 >

  11. [Ⅰ] Previous experimental results • 13 MeV pp-QFS cross sections (at q1= q2, q1＜ q2). 13 MeV q 1＜ q 2 q 1 = q 2 q2 [deg] QFS exp. / calc. q1 [deg] < APFB2011 >

  12. [Ⅰ] Previous experimental results • 9.5 MeV pp-QFS cross sections (at q1= q2, q1＜ q2). 9.5 MeV q 1＜ q 2 q 1 = q 2 q2 [deg] exp. / calc. QFS q1 [deg] < APFB2011 >

  13. [Ⅰ] Previous experimental results • pp-QFS cross sections at several detection angles (at q1= q2, q1＜ q2) agreed with the pd calculation. • We confirmed there is no pp-QFS anomaly at 9.5 & 13 MeV. exp. / calc. exp. / calc. < APFB2011 >

  14. [Ⅱ] Present experiment • Energy dependence of QFS cross section • We confirmed there is no anomaly at 9.5 & 13 MeV. • In our present experiment, we measured pp-QFS cross section at 19 MeV. NEXT 19 < APFB2011 >

  15. [Ⅱ] Experimental procedure at 19 MeV • Facility : Accelerator center @ University of Tsukuba • Beam : 19 MeV unpolarized proton beam ( ~ 150 nA) • Target : CD2 foil ( ~ 0.4 mg/cm2) mounted on a rotary target • Detectors : Si-SSD • Observable : Differential cross section of the 2H(p,pp)n reaction on pp-QFS • Detection angle : (q1, q2, Δf12)=(41.0°, 41.0° , 180.0°) pp-QFS Lab system < APFB2011 >

  16. [Ⅱ] Setup in scattering chamber • - coincident detection • We measured E1, E2, T2－T1. • Monitor → Detect pd-elastic scattering events simultaneously. E1 E2 < APFB2011 >

  17. [Ⅱ] Strong points • ① We used an unpolarizedp-beam in order to measure ONLY cross section. • ② We mounted a CD2 foil on a rotary target. • More stable measurement than a fixed target. p-beam ① Unpolarized beam ② Rotary target Rotary Thickness [mg/cm2] Fixed Time [h] < APFB2011 >

  18. [Ⅱ] Strong points • ③ We used well-defined apertures for the housings of detectors. • Precise determination of each solid angle ③ Well-defined apertures ① Unpolarized beam ② Rotary target Ordinary mechanical machining edge Electric discharge machining edge Aperture Smooth Not smooth < APFB2011 >

  19. [Ⅱ] Data analysis pd-breakup cross section Raw data 19 MeV ● present E2 [MeV] S S [MeV] S = 0 E1 [MeV] S : arc length from S=0 point < APFB2011 >

  20. [Ⅱ] Time-of–Flight (TOF) method True+B.G. gate True+B.G. Raw data Counts/0.5 MeV True+ B.G. E2 [MeV] E2 [MeV] S S B.G. S = 0 S = 0 B.G. only gate S [MeV] E1 [MeV] E1 [MeV] Remove B.G. B.G.only pd-breakup events T(E2)–T(E1) [ns] E2 [MeV] Counts/0.5 MeV True S = 0 T2–T1 [ns] S [MeV] E1 [MeV] Li : distance from target to detector < APFB2011 >

  21. [Ⅱ] Determination of absolute value pd-breakup cross section pd-breakup events Estimate pd-breakup cross section Monitor pd-elastic cross section 0.5 MeV pd-elastic scattering events Geometrical measured ・Distance (From target to detector) ・Aperture size Counts/Channel From experimental data (K. Sagara et al (1994)) Channel < APFB2011 >

  22. [Ⅱ] Present experimental result at 19 MeV • 19 MeV pp-QFS cross section • Total systematic error is about ±4%. • Experimental data shows a good agreement with the pd calculation. • Systematic errors • Monitor cross section : ±0.3% • Solid angles • Monitor SSD : ±0.3% • Breakup SSD : ±2.3% • pd-elastic events : ±2 % • Others : ±1 % • Total error about : ±4 % ● present 19 MeV ○ Koeln ― pd pd+Δ nd QFS S [MeV] Calc. by A. Deltuva et al. (2005) < APFB2011 >

  23. [Ⅱ] Present experimental result at 19 MeV • Energy dependence of QFS cross section • We conclude there is no pp-QFS anomaly at 19 MeV. • We guess there is also no pp-QFS anomaly at 16 MeV. • We measured a cross sectionat 7.5 MeV. 19 MeV 19 13 □ CIAE (2007) 9.5 ○ Bonn (2002) s (exp.) / s (calc.) □ Koeln (72’, 91’, 96’) QFS ○ Grenoble (1972) 7.5 ● KUTL (2009) Preliminary ● KUTL (Present) Calc. by A. Deltuva et al. (2005) Energy [MeV] < APFB2011 >

  24. [Ⅱ] Preliminary experimental result at 7.5 MeV • 7.5 MeV pp-QFS cross section • Statistical error is about ±3%. • Experimental data shows an almost good agreement with the pd calculation. ● preliminary 7.5 MeV ― pd+D pd QFS S [MeV] Calc. by Ishikawa < APFB2011 >

  25. Summary • We made systematic measurements on pp-QFS cross section, previously at 9.5 & 13 MeV, recently at 19 & 7.5 MeV. • We compared the data with the pd calculation by A. Deltuva et al (2005). • From our experiments, • All of the results show good agreements with the pd calculation. • There are no pp-QFS anomaly at 7.5, 9.5, 13, and 19 MeV contrary to pd SS anomaly around 30 MeV. • We guess • No pp-QFS anomaly at 16 MeV, and also at higher incident energies. • We have not known whether nn-QFS anomaly is true or not. < APFB2011 >

  26. Comparison of experimental conditions 19 MeV < APFB2011 >

  27. Comparison of CD-Bonn & AV18 7.5 MeV ~4% 13 MeV 9.5 MeV 19 MeV ~4% ~2% By A. Deltuva, CD-Bonn By Ishikawa, AV18 < APFB2011 >

  28. 19 13 □ CIAE (2007) 9.5 ○ Bonn (2002) s (exp.) / s (calc.) □ Koeln (72’, 91’, 96’) ○ Grenoble (1972) 7.5 ● KUTL (2009) ● KUTL (Present) Energy [MeV] < APFB2011 >

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