development of the neutron development of the neutron counters for the Spin dipole counters for the Spin dipole

resonanceresonance

Kazuhiro IshikawaKazuhiro Ishikawa

Our group experimentOur group experiment

test experiment for the newly developed the neutron counters to measure the spin dipole resonance 　 (SDR reaction) .

Simulation for the neutron counters by the Geant4

My research thesis

フローチャートフローチャート

nn 検出検出↑↑d *singlet → p-nd *singlet → p-n↑↑　　　　 ( d, d* singlet )( d, d* singlet )↑↑　　（　　、　　　　（　　、　　 ) ) 　　 　　　 　 (spin dipole (spin dipole

resonance)resonance)↑↑Super nova (cooling mechanism)Super nova (cooling mechanism)

O16

　　 The condition of Supernova's explosion and the cooling velocity The condition of Supernova's explosion and the cooling velocity of neutron star is determined by the neutrino.of neutron star is determined by the neutrino.

Mainly μ-neutrino and τ-neutrino is emitted by these reaction Mainly μ-neutrino and τ-neutrino is emitted by these reaction If we detect their neutrino, we can get the important information If we detect their neutrino, we can get the important information

of Supernovaof Supernova . .

SDR is used to detect the μ- neutrino and the τ- μ- neutrino and the τ- neutrino.neutrino.

O16

We observe μ-neutrino τ-through by using the spin dipole resonance We observe μ-neutrino τ-through by using the spin dipole resonance (SDR) reaction.(SDR) reaction.We measure γ- decay on the 16O.We measure γ- decay on the 16O.

SDR research is not made progress so much. SDR research is not made progress so much. We must firstly establish the probe SDR excited.We must firstly establish the probe SDR excited.We substitute the deuteron for the neutrino ,d(We substitute the deuteron for the neutrino ,d( 　　　　　　 , )d* singlet ., )d* singlet .*16 O

What is the SDR reaction?What is the SDR reaction?

Next state is J+=0-or 1- or 2- .Next state is J+=0-or 1- or 2- .

SDR reaction change ΔSSDR reaction change ΔS ＝１ ＝１ and ΔLand ΔL ＝１ ＝１ and ΔTand ΔT ＝１ ＝１ compared initial state.compared initial state.

Excited 16O* decay into 15N or 15O emitting γ-Excited 16O* decay into 15N or 15O emitting γ-ray. ray. (particle threshold 15N=10.2Mev,15O=7.3Mev)(particle threshold 15N=10.2Mev,15O=7.3Mev)

How to select the How to select the

d + → 　 d*singlet + (d*singlet is )

.

state exhausts 85% of the cross section under 0.5Mev in the p-n relative energy.

To obtain the SDR cross-sectionTo obtain the SDR cross-section

(d*singlet,p-n) →Energy spectrum of

relative energy E → 　 select of

Example in the (d,pn)Example in the (d,pn)

The purpose of simulating a new The purpose of simulating a new neutron counter.neutron counter.

resolution to be reachedresolution to be reached angular resolution angular resolution 　 　 energy resolutionenergy resolution

We need almost the same performance neutron counter as the proton detector.We need almost the same performance neutron counter as the proton detector.We simulate the neutron counter by using geant4 .We simulate the neutron counter by using geant4 .

proton detector resolution at the smartproton detector resolution at the smart

Optimization of detector dimensions to detect 1S0 state.

Definition of geometry Definition of geometry

sincilator definitionbc408 density 1.032g/cmrefraction rate 1.58H/C 1.104

Total volume(6 planes×5 layers ）60cm×15cm×60cm

Included in the scintilatorIncluded in the scintilator Interaction definition Interaction definition

γ γ 　 　 photoelectric effect, compton scatteringphotoelectric effect, compton scattering

　　　　 　　　　 pair production pair production

multiple scattering, ionisation multiple scattering, ionisation ｌｏｓｓ ｌｏｓｓ ｂｒｅｍｓｓｔｒａｈｌｕｎｇａｎｎｉｈｉｌａｔｉｂｒｅｍｓｓｔｒａｈｌｕｎｇａｎｎｉｈｉｌａｔｉ

ｏｎ ｏｎ p elastic scattering ,inelastic scattering p elastic scattering ,inelastic scattering

ionisation loss ,multiple scattering ionisation loss ,multiple scattering

n elastic scattering, inelastic scattering n elastic scattering, inelastic scattering

neutron capture neutron capture

d ,α, ion elastic scattering, ionisation, multiple - d ,α, ion elastic scattering, ionisation, multiple -

scattering scattering

Result of simulationResult of simulation Energy lossEnergy loss

↓ 　 135MeV neutron beam

time informationtime information

Resolution(0.4ns) is caused by thickness of scintilator.

↓ 　 135MeV neutron beam

efficiency efficiency

energy calculated from TOFenergy calculated from TOF

Resolution is 0.4MeV

The 7Li(p,n)7Be test experimentThe 7Li(p,n)7Be test experiment

obtain the efficiency in the new obtain the efficiency in the new neutron counter .neutron counter .

obtain the energy resolution on the obtain the energy resolution on the target.target.

Beam source is .Beam source is .

Experiment institutionExperiment institution

ＲＡＲＦ

smartsmart

First focal plane(F1) Second focal Plane(F2) Magnetic elements QQD QQDQD First order resolving power 4000 12000 Mean orbit radius 2.4 m 2.4 mMaximum magnetic field 1.5 T 1.5 T Typical Angular resolution 5-25 mrad 3 mrad

Experimental resultExperimental result7Li(p,n)7be

Resolution is 2.6MeV.

efficiencyefficiency

To develop the excellent neutron To develop the excellent neutron countercounter

We must multiple sincilator to increase We must multiple sincilator to increase efficiency.efficiency.

We must remove more the γ-ray and th We must remove more the γ-ray and th e particle ….d,p etc.e particle ….d,p etc.

We must improve the beam qualityWe must improve the beam quality. .