Measurement of pd breakup cross sections at E/A = 13 MeV in the off-plane star configuration Yukie Maeda (University of Miyazaki) H. Shimoda, K. Sagara, S. Kuroita, T. Sueta, Y. Eguchi, K. Yashima (Kyushu Univ.) A. Nonaka, N. Fujita (Univ. of Miyazaki) D. Ishikawa, K. Hatanaka, H. Okamura, A. Tamii (RCNP, Osaka Univ.) FB /8/31

1 Introduction Study of the three-nucleon system at low energy region  DCS of elastic scattering  3NF effect is small  NN + 3NF+ Coulomb reproduce the data well Kievsky et al, PRC64 (2001) Spin observables still have some problems (Ay puzzle etc) But Cross sections are explained sufficiently !!

2 pd breakup low energy Study at 13MeV for some configurations （ solid ： pd, open ： nd ）  Quasi-free scattering (QFS)  Final state interaction (FSI)  Introduction of the Coulomb into the calculation improved the predictions.  Some discrepancies are left to be explained.  Space-star (SST)  Large discrepancy between the data of pd and nd can not be explained by the Coulomb effects.  The theoretical prediction overestimates the pd data about 20%. A. Deltuva et al, PRL95 (2005) SST QFS FSI CD Bonn +  +Coulomb CD Bonn +  △

3 Off-plane star configurations Definition in this talk: The  is the angle between p-beam axis and the equilateral trianglr plane which include the momentum of p1’, p2’, n’ in the c.m. system. α=90° Space Star. α= 0, 180° Coplanar Star. α≠0,180° Off-plane Star.

4 Data from Köln J. Ley et al, PRC73 (2006) CD Bonn CD Bonn +  CD Bonn +  +Coulomb 1 H(d,pp) breakup measurement at E d =19MeV (9.5MeV/A) at Köln  3NF effects slightly improve the theory by 5 – 8%.  The predictions with 3NF and Coulomb effects still overestimate the data up to 30%. Off-plane-star anomaly

5 Motivation We performed the measurements of 1 H(d,pp) breakup reactions at E d = 26 MeV at RCNP  Off-plane star anomaly is truly exist or not?  Systematical study of the discrepancy between the data and the theory  Measurements for some other configurations (SST, FSI) of pd breakup reactions have performed at E p = 13 MeV at KUTL tandem accelerator, Kyushu University. Off-plane star configuration measurements of 2 H(p,pp) at E p = 13 MeV at KUTL.  Range of  = 0 – 180 deg will be covered by the data of RCNP & KUTL

6 Experimental procedure 1 H(d,pp) breakup reactions at E d = 26 MeV  26MeV deuteron beam from AVF  Proton target ; CH 2 (polyethylene)  Two proton detection; 3pairs of SSDs  Luminosity monitor  dp elastic scattering  Configurations   = 120, 140, 160, 180 deg Skip beam line d-beam CH 2 F.C. Monitor Left detectors p1 p2 Right detectors

7 Setup Two protons detection by using a pair of 3000  m t SSD (Si-Li) d-beam CH 2 F.C. Left detectors p1 p2 Right detectors  RL RR LL  R  L 180°22.0°0.0°180.0° °22.7°11.2°168.8° °24.5°20.4°159.6° °27.1°26.6°153.4° (msr) Monitor SSD:  = 35.0  =0  R =0.0306(msr)  Monitoring of the target thickness by measuring the pd elastic scattering Calibration of the solid angles of each detectors  Measurement of the C+p elastic scattering at  = 35.0 by using each SSD and Monitor-SSD simultaneously

8 Rotary target Simulation  At 20 r.p.m., the temperature of the target foil increases only 15 degrees. Beam Beam spot Atmosphere Inside Scattering chamber Motor Rotation feedthrough Beam Line Deutron 26MeV 200nA, 0.3mg/cm2 Rotary target system  Through magnetic coupling, a shaft in a vacuum chamber is rotated by a motor in the air.  The target foil : 5cm diameter.  Rotation speed : 20 r.p.m.  Rotary target can be lift up in vacuum, and other foil targets can be used in turn.

9 Uniformity of the target thickness Thickness of a CH2 rotary target was constant for 20 hours. Stationary CH 2 target 25 ℃ →100 ℃ (Beam Intensity : 100nA) Rotate CH 2 target 25 ℃ →40 ℃ (Beam Intensity : 200nA) Change of CH 2 thickness Time (hour) High luminosity was obtained without the decrease of CH 2 target thickness!

10 Analysis Most of the data is the accidental coincidence events  Event selection by using the information of the time difference between p1 and p2 C(d,d) H(d,p) C(d,d1) breakup H(d,d) Single energy spectrumE1-E2 spectrum after TOF gate S-curve of true events d-beam E1E1 E2E2 CH 2 detect T1T1 T2T2

11 Results DCS Theoretical predictions can reproduce the data well.

12 Systematic error Derivation of the data  Sagara et. al, PRC50,576 (1994)  1,  2 +/- 2.6%  mon +/- 1.5% Y 12 +/- 1.0% Y mon +/- 0.5% total +/- 4.1% List of the error source

13 Angular & energy dependence Ratio of data/calc. at the star configuration  We can not see the large anomaly in the backward region at 13MeV/A, which is different from the Köln data at 9.5MeV/A.  More experimental studies are needed to see the energy dependence of the anomaly. This work

14 Summary To study the off-plane star anomaly, we performed the experiment of 1 H(d,pp) and 2 H(p,pp) breakup reactions at E/A = 13MeV at RCNP and KUTL.  Si-Li type SSDs were used for detecting 2 protons in coincidence.  Rotary target system allowed us to obtain high luminosity.  The differential cross sections for  = 120 ~ 180 deg (RCNP) and 0 ~ 75 deg (KUTL) were measured. From the comparison between the data and the theoretical predictions;  The data at 13MeV/A can be well reproduced by the calculations including the Coulomb effects, which is different from the data of Köln.  It is better to perform the experiment at E d = 19MeV at RCNP to confirm the large anomaly reported from Köln.

15 END

16 SCRE configurations Off-plane star configuration   =0 (coplanar star), 17.7, 36, 56 deg  Two proton detection in coincidence by a pair of SSDs. Differential cross sections and Tensor analyzing powers  Normalization: dp elastic scattering  Rawdata; E 3, E 4,  t E1 E2

17 実験値導出 微分散乱断面積 偏極分解能  pd elastic scattering