Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2010) 1–2

Development of InP solid state detector and liquid scintillator containing indium
complexes for a measurement of pp/7 Be solar neutrinos
Yoshiyuki Fukuda for IPNOS collaboration
Faculty of Education, Miyagi University of Education, 149 Aramaki-aza-Aoba, Aoba-ku, Sendai, Miyagi 980-0845, Japan

Abstract
Am semi-insulating indium phosphide detector has been developed for IPNOS experiment and it could detectboth γ’s and the scintillation light. We have also developed an organic liquid scintillator which contains indium andzirconium complexes, and found the gamma-ray-induced luminescence of 8-quinolinol metal complexes.
Keywords: solar neutrinos, solid state detector, liquid scintillator, double beta decay

1. Performance of InP detector

then the expected yield should be ∼ 10keV equivalent.

For observation of pp/7 Be solar neutrinos, the following reaction 115 In + νe →115 Sn∗ + e− could haveadvantages that (1) large cross section, (2) low energy
threshold and (3) triple coincidence (e+γ1 +γ2 ) to extract signal [1]. We have developed semi-insulating InP
detector for IPNOS experiment. Two γ’s might escapefrom the InP detector, so that the liquid scintillator suchas liquid xenon should be used for both detecting γ’sand coolant of InP detector.
In order to detect scintillation light, we have developed InP detector (6mm × 6mm × 20µm) with thin electrodes which consist of Cr/Au (10/10nm). The scintillation light was used for CsI which irradiated by 241 Am αsource. This detector could detect both γ’s and scintillation light. The transparency of Au/Cr electrodes
were estimated by 0.57 × 0.37 = 0.21, and observed
charge were 0.5 ∼ 2.0fC. Therefore, the photon conversion efficiency was obtained by 0.3. In case of liquid xenon, the transparency of Au/Cr electrode will be
0.43 × 0.39 = 0.17, and assuming same conversion efficiency and photon coverage to be 0.8, the expected
scintillation yield will be ∼ 3keV equivalent. This is
not enough for the detection, so that we have to modify shape of electrode. Assuming 50% for naked area of
InP surface, the transparency will be recovered by 0.58,

2. Liquid scintillator containing metal complexes
An organic liquid scintillator containing indium andzirconium complex were studied for low energy solar
neutrinos and double beta decay, respectively. We havechosen tris (8-quinolinolato) complex which has photoluminescence. Benzonitrile was also chosen as a solvent
because of good solubility for the complexes ( 2 wt%)
and good light yield. The photo-luminescence emission
spectra of InQ3 and ZrQ4 in benzonitrile was measured.
The emission maxima for InQ3 and ZrQ4 were foundat 559nm and 548n, respectively. We prepared 50mg
of complex in benzonitrile solutions (20 mL). Two secondary scintillators, 100 mg of PPO and 10 mg ofPOPOP, are also dissolved as a wavelength shifter. Theenergy spectra of electrons emitted by Compton scattering of incident gamma-ray using 60 Co was obtained.
The quantum yield was obtained by 15.6% and 11.5%,respectively. We will modify 8-quinolinolate ligand toadd substituent groups in order to both increase quantum yield and shorten wavelength of luminescence.
References[1] R.S.Raghavan Phys. Rev. Lett. 37 (1976) 259.