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 Department of Physics, Kyushu University, 1 Department of Applied Physics, University of Miyazaki, 2 Department of Physics, University of Tsukuba

Anomalies in N + d (p + d & n + d) reactions Low energy region below about 30 MeV A y  reactionAnomaly #1. Space Star anomaly (  ) #2. Quasi - Free Scattering anomaly (  )

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

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

Low energy region in pd - breakup reaction QFS anomaly has been also reported from some experiments. #2. Quasi - Free Scattering (QFS) anomaly Koeln pp - QFS Lab system nn - QFS Lab system Bonn 19 MeV26 MeV

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. #2. Energy dependence of QFS anomaly  (exp.) /  (calc.) Energy [MeV] nd exp. > nd calc. pd exp. < pd calc. ○ Bonn (2002) □ CIAE (2007) □ Koeln (72’, 91’, 96’) ○ Grenoble (1972)

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. Motivation pp - QFS nn - QFS

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. [ Ⅰ ] Previous KUTL pp - QFS Lab system

Result at 13 MeVResult at 9.5 MeV [ Ⅰ ] Previous experimental results 9.5 & 13 MeV pp - QFS cross sections (at   1    2  QFS

Energy dependence of QFS cross section [ Ⅰ ] Previous experimental results  (exp.) /  (calc.) Energy [MeV]   1    2 1＜21＜2 Next Change the detection angle Additional experiments ○ Bonn (2002) □ CIAE (2007) □ Koeln (72’, 91’, 96’) ○ Grenoble (1972) ● KUTL (2009)

13 MeV pp - QFS cross sections (at   1    2,   1  ＜   2  [ Ⅰ ] Previous experimental results QFS 13 MeV   1 [deg]   2 [deg] exp. / calc.  1  2  1  ＜  2

9.5 MeV pp - QFS cross sections (at   1    2,   1  ＜   2  [ Ⅰ ] Previous experimental results QFS 9.5 MeV exp. / calc.   1 [deg]   2 [deg]  1  2  1  ＜  2

pp - QFS cross sections at several detection angles (at   1    2,   1  ＜   2  agreed with the pd calculation. We confirmed there is no pp - QFS anomaly at 9.5 & 13 MeV. [ Ⅰ ] Previous experimental results exp. / calc.

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. [ Ⅱ ] Present experiment 19 NEXT

[ Ⅱ ] Experimental procedure at 19 MeV Facility : Accelerator University of Tsukuba Beam : 19 MeV unpolarized proton beam ( ~ 150 nA) Target : CD 2 foil ( ~ 0.4 mg / cm 2 ) mounted on a rotary target Detectors : Si - SSD Observable : Differential cross section of the 2 H(p,pp)n reaction on pp - QFS Detection angle : (  1,  2, Δ  12 ) = (41.0°, 41.0°, 180.0°) pp - QFS Lab system

- coincident detection We measured E 1, E 2, T 2 － T 1. Monitor → Detect pd - elastic scattering events simultaneously. [ Ⅱ ] Setup in scattering chamber E1E1 E2E2

① We used an unpolarized p - beam in order to measure ONLY cross section. ② We mounted a CD 2 foil on a rotary target. More stable measurement than a fixed target. ① Unpolarized beam [ Ⅱ ] Strong points ② Rotary target Time [h] Thickness [mg /cm 2 ] Rotary Fixed p - beam

③ We used well - defined apertures for the housings of detectors. Precise determination of each solid angle [ Ⅱ ] Strong points ③ Well - defined apertures Electric discharge machining edge ① Unpolarized beam ② Rotary target Ordinary mechanical machining edge SmoothNot smooth Aperture

[ Ⅱ ] Data analysis S = 0 E 1 [MeV] E 2 [MeV] Raw data S [MeV] pd - breakup cross section S S : arc length from S = 0 point ● present 19 MeV

S = 0 [ Ⅱ ] Time - of – Flight (TOF) method E 1 [MeV] E 2 [MeV] T (E 2 ) – T (E 1 ) [ns] T 2 – T 1 [ns] E 1 [MeV] E 2 [MeV] E 1 [MeV] E 2 [MeV] Raw data S S True + B.G. gate True + B.G. B.G. only B.G. only gate True + B.G. B.G. True S [MeV] Counts / 0.5 MeV Remove B.G. pd - breakup events S = 0 L i : distance from target to detector

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

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 % [ Ⅱ ] Present experimental result at 19 MeV S [MeV] ○ Koeln ● present ― pd pd + Δ nd QFS Calc. by A. Deltuva et al. (2005) 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 section at 7.5 MeV. [ Ⅱ ] Present experimental result at 19 MeV  (exp.) /  (calc.) Energy [MeV] 19 MeV 7.5 Preliminary Calc. by A. Deltuva et al. (2005) QFS ○ Bonn (2002) □ CIAE (2007) □ Koeln (72’, 91’, 96’) ○ Grenoble (1972) ● KUTL (2009) ● KUTL (Present)

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

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. Summary

Comparison of experimental conditions KUTLKoeln Beam Unpolarized p - beam to measure only  E p = 19 MeV, 150 nA Polarized p - beam to measure , A y  E p = 19 MeV, 200 nA Target Rotating CD 2 foil 50 mm in diameter 0.4 mg / cm 2 in thickness Rotating CD 2 foil 0.1 mg / cm 2 in thickness DetectorsSi - SSD Solid angle for p 1 & p msr, 0.58 msr0.66 msr, 0.85 msr Aperture edge Electric discharge machining No information pd - breakup  evaluation pd - elastic scattering  used. 19 MeV

Comparison of CD-Bonn & AV18 ~4 %~2 % By A. Deltuva, CD-Bonn By Ishikawa, AV MeV 13 MeV 9.5 MeV19 MeV ~4 %

 (exp.) /  (calc.) Energy [MeV] 7.5 ○ Bonn (2002) □ CIAE (2007) □ Koeln (72’, 91’, 96’) ○ Grenoble (1972) ● KUTL (2009) ● KUTL (Present)