Discrepancy in pd Breakup Reaction at Ep = 13 MeV

K. Sagara, M. Tomiyama, S. Shimomoto, T. Ishida, T. Kudoh, S. Kuroita, T. Morikawa, M. Shiota, H. Ohira,

*H. Kamada and **H. Witala

Dept. of Physics, Kyushu University, Fukuoka, Japan*Dept. of Physics, Kyushu Institute of Technology, Kita-Kyushu, Japan,

**Dept. of Physics, Jagiellonian University, Cracow, Poland

Backgrounds:Ay puzzle in pd and nd scattering exists at 0 < Ep and En < 30 MeV. Space Star (SS) anomaly in nd breakup is most prominent at En=13 MeV. 23NF effects are too small to explain these discrepancies. Questions: Does SS anomaly appear also in pd breakup at 13 MeV?Are there further discrepancies in pd breakup at 13 MeV?

Experiments:We made three measurements at Ep =13 MeV1) D(p,pp)n experiment at pp FSI2) D(p,p)pn experiment at p =10deg ~60 deg3) D(p,pp)n experiment at many angle pairs around SS

A new method to estimate Coulomb effects: Watson&Migdal-Faddeev approximation for pd breakup cross sectionis compared with pd calculation by Deltuva et al.

Outlook

Ay puzzle:Systematic measurement of pd scattering Ay at Ep =2-18 MeV at Kyushu University (1994)

Tornow talked about nd Ay puzzle on Monday. Ay puzzle is still an open problem since 1986.

Space Star anomaly

nd exp. Erlangen & TUNL

pd exp.Koeln

nd calc.

D(n,nn)p at En =13 MeVD(p,pp)n at Ep =13 MeV

Energy Dependence of SS

Questions:Does SS anomaly exist also in pd breakup at 13 MeV?Are there other discrepancies in pd breakup at 13 MeV?

We made three experiments at 13 MeV: 1) D(p,pp)n experiment at pp FSI to study the treatment of Coulomb effects

2) D(p,p)pn experiment at p = 10deg ~60 deg to see global feature of breakup cross section

3) D(p,pp)n experiment at wide angular range around SS to see angular dependence of SS anomaly

1=2= 20 deg. : φ12= 16.3 deg.

θ1=θ2= 30 deg. : φ12= 11.2 deg.

θ1=θ2= 40 deg. : φ12= 8.7 deg.

Experiment (1)Ep =13 MeV D(p,p1p2)n near pp-FSI

D(p,p1p2)n Ep=13MeV data

E1 vs. E2

S-curve

FSI

E1 vs. E2

back ground

(TOF gated)

20 deg.

ΔT1-ΔT2 vs. ΔT(E1,E2) (Energy gated)

Comparison with nd-Faddeev calc. Watson-Migdal pp FSI calc.

Faddeev calc. by H. Kamada

D(p,pp)n at 13 MeV

Watson-Migdal FSI Formula

Scattering length

Effective range

Coulomb penetration factor

Sommerfeld parameter

Slowly varying function

nd breakup　 nn-FSI

pd breakup pp-FSI

F(nd) = f(n1n2) + f(n1p) + f(n2p)

F(pd) ≈ f(n1n2)x(WMpp/WMnn) + f(n1p) + f(n2p)

WMnn(Enn)

WMpp(Epp)

(WMpp/WMnn) (WMpp/WMnn)

40 0 20 40ENN(MeV) ENN(MeV)2

ENN(MeV)

n+n+p calculation ↓ p+p+n calculation

0

1

2

0 2 4 6 8

D(p,pp)n Ep =13MeV 1=2=40deg, 12=8.7deg

S

WM-Faddeev calculation gives nearly the same results as pd calculation by Deltuva et al.

WM-Faddeev calculation Calc. by Deltuva et al

Experiment (2):D(p,p)pn cross section at p = 10~60 deg at Ep = 13 MeV

13 MeV p

D2 gas / vacuum

13 MeV p

D2 gas / vacuum / H2 gas

4m Al foil

2.2m Havar foil

For 20degree < p

For p ≤ 20degree

D(p,p)pn at 10 degreeD2 target

vacuum target

H2 target – vacuum target

Ep (channel)

0

5

10

15

20

0 2 4 6 8 10 12

D(p,p)np E=13 MeV, 50 deg

Ep (MeV)

0

5

10

15

20

25

0 2 4 6 8 10 12

D(p,p)np E=13 MeV, 40 deg

Ep (MeV)

0

5

10

15

20

25

0 2 4 6 8 10 12

D(p,p)np E=13 MeV, 30 deg

Ep (MeV)

WM+Faddeev Deltuva etal.

0

5

10

15

20

25

30

0 2 4 6 8 10 12

D(p,p)np E=13 MeV, 10 deg

nd2NFpd2NFnd3NFpd3NFExpAExpB

Ep (MeV)

0

5

10

15

20

25

30

0 2 4 6 8 10 12

D(p,p)np E=13 MeV, 15 deg

nd2NFpd2NFnd3NFpd3NFExpAExpB

Ep (MeV)

0

5

10

15

20

25

30

0 2 4 6 8 10 12

D(p,p)np E=13 MeV, 20 deg

nd2NFpd2NFnd3NFpd3NFExpAExpB

Ep (MeV)

Preliminary data

Tentative conclusion: In D(p,p)pn inclusive cross section at p = 10 ~ 60 degree, no discrepancy has been found.

15 degree 20 degree10 degree

Experiment (3):D(p,pp)n cross section at around Space Star at Ep = 13 MeV

p

n

p

1=50.5

2=50.5

12=120

CM system Lab. system

D(p,pp)n cross section was measured at 23 angle pairs around SS configuration (1=50.5, 2=50.5 , 12=120 )

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=50.5 12=120

KUTLKoelnDCBDCBCDCBDC

S (MeV)

Space Star

Present data and Koeln data at SS agree well.

Calc. by Deltuva

nd calcpd calc

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=53.5 12=120

KUTLndpdpdD

S (MeV)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=50.5 12=120

KUTLndpdpdD

S (MeV)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=47.5 12=120

ExpndpdpdD

S (MeV)

47.5-47.5 53.5-53.550.5-50.5

56.0-56.0 63.0-63.059.5-59.5

space star

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=63.0 12=120

KUTLndpdpdD

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=59.5 12=120

KUTLndpdpdD

S (MeV)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14

D(p.pp)n 13 MeV 1=2=56.0 12=120

KUTLndpdpdD

S (MeV)

0

0.2

0.4

0.6

0.8

1

1.2

90 95 100 105 110 115 120 125 130

averaged cross section

exp1exp2exp3pdpdD

1+2 (degree)

space star

1+

2

1

2

averaged cross section

There is a discrepancy in pd breakup cross section around the space star.

Calc. by Deltuva

Summary

Three experiments have been made on 1) D(p,pp)n cross section at pp FSI2) D(p,p)pn cross section at p =10deg ~60 deg3) D(p,pp)n cross section at around the space star

Cross section around pp-FSI and D(p,p)pn inclusive cross section are well reproduced by pd calculation by Deltuva et al.

There is a discrepancy (10%-15%) in the cross section around the space star.

Watson&Migdal-Faddeev approximation was found to be a simple and effective method to estimate pd breakup cross section.