measurement of 2 h( p,pp )n cross sections at e p = 250 mev

Dept. of Phys., Kyushu Univ.Dept. of Phys., Kyushu Univ.

Measurement of 2H(p,pp)n cross sections at Ep = 250 MeV

Sho Kuroita1,K. Sagara1, Y. Eguchi1, K. Yashima1, T. Shishido1, T. Yabe1,

M. Dozono1, Y. Yamada1, T. Wakasa1, T. Noro1, H. Matsubara2

J. Zenihiro2, A. Tamii2, H. Okamura2, K. Hatanaka2, T. Saito3

Y. Maeda3, H. Kamada4, Y. Tameshige5

1: Department of Physics, Kyushu University2: Research Center for Nuclear Physics (RCNP), Osaka University

3: Department of Applied Physics, University of Miyazaki4; Department of Physics, Faculty of Engineering, Kyushu Institute of Technology

5: National Institute of Radiological Sciences

Dept. of Phys., Kyushu Univ.

1957 Fujita – Miyazawa suggested the existence of three nucleon force.Then 2p-exchange three nucleon force (2p3NF) models were created, and these 2p3NF well described binding energies of nuclei were constructed by few nucleon.

Differential cross sections of pd scattering below EN = 140 MeV were well described by including 2p3NF in Faddeev calculations.

Introduction 1

2009/9/3 2FB19 - Bonn University, Germany

Cross sections of pd elastic scattering at Ep = 65, 140 MeV

NN + TM3NFNN only

H. Witala et al., PRL81 (1998) 1183.

NN only NN+TM-3NF

CD Bonn 8.0 MeV 8.5 MeVNijm II 7.6 MeV 8.5 MeVAV18 7.6 MeV 8.5 MeVExp. 8.5 MeV

65 MeV 140 MeV


FB19 - Bonn University, Germany

Introduction 2Besides 2p-exchange 3NF, heavy-meson exchange 3NF are predicted in cPT.

These heavy-meson exchange 3NFs are expected that the effects become larger at high energy region.

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Study by elastic scattering

Above EN = 140 MeV, cross section of pd elastic scattering does not described by Faddeev calculation with 2π3NF.

2009/9/3 4

EN = 250 MeV Nd elastic scatteringK. Hatanaka et al., PRC66 044002 (2002).Y. Maeda et al., PRC76 014004 (2007).

NN + TM3NF NN only

＊ The disagreement of pd elastic scattering become larger at higher incident energy.

＊ And the disagreements are not related to π-thresholdp-threshold



So we have measured cross section of pd breakup reaction in order to investigate origins of the disagreement on Nd scattering cross section.

We measured cross section and analyzing power Ay of inclusive pd breakup 2H(p,p)pn reaction at Ep = 247 MeV to study the global feature of pd breakup reaction at intermediate energy region.

Study by pd breakup – 2H(p,p)pn reaction --

2009/9/3 5

At intermediate energies, Nd breakup reaction is main reaction process in 3N systems.

J. Kuros-Zoluierczuk et al.,PRC66, 024003 (2002).

Observable : cross section, Ay (E = 70 ~ 230 MeV)Angle : 10, 15, 20 deg. Detector : Spectrometer (LAS@RCNP) VDC, ScintillatorTarget : Liquid Deuterium

Calc. by H. Witala, private communication

detected

p1

Angle is free !




2009/9/3 6

nd calculation by Prof. H. Witala

Even after inclusion of 2π3NF , large disagreements remain.The experimental cross section is about 1.8 times larger than calc. at 15 deg .

First, we pay attention to only the disagreement of cross sections.




2009/9/3 7

pd calculation by A. Deltuva

pd calculation indicate Coulomb effect slightly decreases cross section.To sum up, the orign(s) of the disagreement is not Coulomb effcet.



Relations between 2H(p,p)pn and 2H(p,pp)n2H(p,p1)pn reaction == previous experiment ==

2H(p,p1p2)n reaction == New experiment ==

2009/9/3 8

detected

p1

Angle is free !

q1 = 15°fixedE1 = 150 MeV

q2



Prediction from calculationDependence of cross section for q2

d3s/dW1dW2dE(15f, 150 MeV, q2, 180f)3N calculation for 2H(p,p1p2)n reaction at 250 MeV suggests that 2H(p,pp)n cross section has the maximum at q2 ~ 35 deg.

Dependence of cross section for f12

d3s/dW1dW2dE(15f, 150 MeV, 35f, f12)Also 3N calculation suggests that 2H(p,p1p2)n cross section has the maximum at f12 = 180 deg. So we measure cross section at f12 = 180 deg.

2009/9/3 9

Calc. by Prof. H. Kamada

q2

f12



Experiment2H(p,pp)n breakup reactions at Ep = 250 MeV

250 MeV proton beam from RING cyclotron @ RCNPWS course in West exp. RoomObservable : Cross sectiontarget : Liquid deuterium

CD2

Detector : GR (spectrometer) LAS (spectrometer) Scintillator

Luminosity monitordp elastic scattering(kinematical coincidence)

Configuration2H(p,p1p2)n reactionq1 (GR) = 15 deg fixedq2 (LAS) = 35, 50, 65, 80 deg

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Scatt. Chamber * Liq. D2

GR

LAS



Target – Liquid deuterium --We used liquid deuterium target system as deuteron target . Liquid deuterium target is an almost pure and very thick deuteron target, and it enables low background experiments.

Thickness : ~ 220 mg/cm2, (target length = ~12 mm)Cell temperature : ~ 18 K (cooled by Cryo – refrigerator)

(monitored by Si diode thermometer)

The thickness of liquid deuterium (liq. D2) target is varied by conditionof cell temperature and gas pressure e.t.c.. So we monitored the thickness by using coincidence measurement of pd elastic scattering simultaneously.

2009/9/3 11

Liq. D2 target cell

expand !

Cryo - refrigerator

Heater



Result -- 2H(p,p1)pn reaction --We have measured cross sections of 2H(p,p1)pn reaction to check the disagreement of the previous 2H(p,p)pn cross sections at 250 MeV in the same setup.

We have reconfirmed the large disagreement of 2H(p,p1)pn cross section between experimental data and Faddeev calculation including 2p3NF.

2009/9/3 12

expand

preliminary preliminary

Calc. by Prof. H. Witala



Spectrum -- 2H(p,pp)n reaction --q1 (GR) = 15 deg, q2 (LAS) = 35 deg, f12 = 180 deg.

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q1 momentum q1 momentum

q 2 m

omen

tum

q 2 m

omen

tum

True + B.G. event

B.G. event

Yiel

d B.G. subtract

E1 [MeV] E1 [MeV]



Result 1 -- 2H(p,p1p2)n reaction --

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q1=15deg, E1=150 MeV


q2=50 degq2=35 deg







2009/9/3 15



q2=80 degq2=65 deg






Trend of 2H(p,p1p2)n cross sectionsDependence of cross section for q2

d3s/dW1dW2dE(15f, 150 MeV, q2, 180f)The cross sections of 2H(p,p1p2)n reaction at 250 MeV have the maximum at q2 = 35 deg. The ratio of the disagreement of2H(p,p1p2)n cross section have alsohas the maximum at q2 = 35 deg.And the ration become smaller at backward angles.

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preliminary

preliminary


16


q2 = 35°,50°,65°,80°




2009/9/3 17



q2=50 degq2=35 deg






ConclusionWe have measured cross sections of 2H(p,p1p2)n reaction atE1 = 150 MeV, q1 = 15 deg fixed, q2 = 35, 50, 65, 80 deg. (total 4 setup).

Simultaneously, we have measured cross section 2H(p,p)pn reaction and confirmed the large disagreement between experimental data and Faddeev calculations including 2p3NF.

The preliminary result of 2H(p,pp)n cross sections suggest large disagreements between experimental data and calculations as same as 2H(p,p)pn reaction. We think that origin(s) of these discrepancy is

Heavy-meson exchange 3NFpr3NF, rr3NF, e.g..

Relativistic effectSo we will have to study relations between these disagreement and candidate of origin(s).

2009/9/3 18

preliminary~ x 1.8



Others disagreementNd elastic scattering (s, Ay, Kij) … RCNP, RIKEN, KVI etc (EN > 140 MeV)

pd radiative capture (s?, Aij) … RCNP (Ed = 200 MeV)

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Motivation 2 -- 2H(p,p)pn reaction --The disagreements of cross sections for 2H(p,p1)pn at 250 MeV become larger at forward angles. Dose the disagreements vanish at backward angle ?

2009/9/3 20

detected

p1123

Previous exp. 2H(p,p1)pn reaction

132

So we have also measured cross sections of 2H(p,p)pn reaction at backward angles to see whether the discrepancy exist at backward angles.



Collinear configurationWhy d3s/dW1dW2dE(15f, 150 MeV, ~35f, 180f) has a maximum ?

When q1 = 15 deg and E1 = 150 MeV, q2 =36 deg, 2H(p,p1p2)n reaction is in “Collinear configuration”. 3N calculations predict cross section has maximum at Collinear configuration.

Whether SR3NF effects dominate in collinear configuration or not is also an interesting subject ?

2009/9/3 21

q1= 15 deg (lab.)E1 = 150 MeV



So we have measured cross section of pd breakup reaction in order to investigate origins of the disagreement on Nd scattering cross section.

We measured cross section and analyzing power Ay of inclusive pd breakup 2H(p,p)pn reaction at Ep = 247 MeV to study the global feature of pd breakup reaction at intermediate energy region.


2009/9/3 22

At intermediate energies, Nd breakup reaction is main reaction process in 3N systems.

J. Kuros-Zoluierczuk et al.,PRC66, 024003 (2002).

Observable : cross section, Ay (E = 70 ~ 230 MeV)Angle : 10, 15, 20 deg. Detector : Spectrometer (LAS@RCNP) VDC, ScintillatorTarget : Liquid Deuterium

Calc. by H. Witala, private communication

measured



Introduction 2So we maybe think that the strength / effects of 2p3NF are also understood by studies of binding energies of nuclei were constructed by few-nucleon and Nd elastic scattering.But others of three-nucleon (3NF) is not found, for example, pr3NF, rr3NF that were the existence expected.Effects of these 3NF may be found at higher energies because these 3NF are the model exchange heavier than p.Besides 2p3-exchange NF, heavy-meson exchange 3NF are redicted in cPT..

2009/9/3 23



2H(p,n)pp @ IUCPThe disagreement of cross section exist at another energies, for example, 2H(p,n) reaction at Ep = 197 MeV by IUCF.

We have already systematic cross section data for 2H(p,p)pn reaction at 250 MeV in wide energy region of reaction protons.If we would performed a experiment for 2H(p,pp)n reaction, we should measure cross section for 2H(p,p)pn to get information of global feature and pp-FSI.

2009/9/3 24

Cross section of 2H(p,n) at IUCFD.L. Prout et al., PRC65 034611 (2002).

In this experiment, cross sections for 2H(p,n) was measured at q = 13, 24, 37,48 deg, and concentrated to QFS.

expand



The discrepancy of 2H(p,p1)pn is the largest at around E1 = 150 MeV .

So we have measured cross sections for 2H(p,p1p2)n reaction around E1 = 150 MeV at fixed q1 = 15 deg. in order to investigation origins for the disagreement of 2H(p,p1)pn.

Motivation 1 -- 2H(p,pp)n reaction --

2009/9/3 25


q2

New exp. 2H(p,p1p2)n reaction (microscopic study)

Previous exp. 2H(p,p1)pn reaction

detected

p1Angle is free !

measurement of 2 h( p,pp )n cross sections at e p = 250 mev

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