Status of the DCBA DCBA Experiment DCBA : D D rift C C hamber B B - PowerPoint PPT Presentation

Status of the DCBA DCBA Experiment DCBA : D D rift C C hamber B B eta-ray A A nalyzer DCBA Nobu ISHIHARA (KEK) for the DCBA collaboration Contents 1. Introduction to DCBA 2. DCBA-T2 in engineering run 3. DCBA-T3 under construction 4. Future prospect of DCBA/MTD Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 1

Introduction to DCBA Momentum analyzers to study ♦ Majorana nature by searching for 0 νββ ♦ Effective neutrino mass by measuring ν 0 T 1 / 2 Advantage of DCBA ♦ Background elimination by particle ID ♦ Characteristic pattern of ββ in a magnetic field ♦ Decay vertex determination ♦ Energy measurement of individual β (e - ) ♦ Angular correlation between ββ Disadvantage ♦ Energy resolution (FWHM ≈ 100 keV) worse than Ge and Te calorimeter ♦ Low detection efficiency ( ≈ 30%) ♦ Large space for decay source installation Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 2

Principle of electron detection in DCBA DCBA Momentum Acceptance p (MeV/c)=0.3 r (cm) B (kG) B ≈ 2 kG 2 cm < r < 5 cm ⇓ 1.2 MeV/c < p < 3 MeV/c Energy Acceptance for e - 0.8 MeV < T < 2.5 MeV Y α is automatically rejected T =1 MeV → p ≈ 87 MeV/c Gas:He(90%)+CO 2 (10%) Z X Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 3

DCBA-T2 X VTX Z β 1 β 2 Drift Chambers 150 Nd Solenoid ( 100 Mo) B plate Magnet VTX Y β 1 β 2 Y Source plate Z X X ( 150 Nd) Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 4

DCBA-T2 drift chamber Pickup 360 540 Anode Pickup Source 440 Plate Source Plate Cathode Anode FRONT VIEW TOP VIEW SIDE VIEW Sensitive vol. : 18(x) × 24(y) × 24(z) [cm 3 ] Gas : He (90%) + CO 2 (10%) Magnet : solenoid magnet 0.6 - 0.8 [kG] Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 5

Straight track of a cosmic ray Y B B1 B1 24 cm Y A1 A1 X X B2 A2 A 7 . 2 c m A2 B Z 2 4cm Z X Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 6

Position resolution of DCBA-T2 σ X σ Y 1.00mm 0.21mm σ Z F i t t e • 0.17 mm d l i n 6 e Measured point • 6 X • Y Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 7

Energy measurement of an I. C. electron from 207 Bi B 207 Bi point source Y Z X y 207 Bi point source x 207 Bi point source Y z X Z x Energy = 1073keV Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 8

Energy resolution of DCBA-T2 Energy spectra of internal conversion electrons from 207 Bi Including Monte Carlo Backgrounds FWHM FWHM ≈ 150keV ≈ 0.15 MeV @980keV 976keV 1050keV Chamber conditions 0.98 1.05 He(90%)+CO 2 (10%) 1atm (7 : 2.4) B=0.8 kG Expected ∆ E/E at Q = 6.3% (FWHM) for 150 Nd Wire pitch=6 mm Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 9

Other BGD events (1) + e α y y − e x x + e z z − α e x Alpha-ray x pair creation Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 10

Double Buffer FADC against Background Events 2e - Background Double buffer FADC − → + β + ν 214 214 Bi Po 83 84 − ↓→ (Q=3.28MeV) conv. e ↓→ + α 210 Pb 82 = µ ( T 164 sec) 1 / 2 160 µ s Memory 1 Memory 2 40 µ s 40 µ s Test pulse input 160 µ s Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 11

Engineering run of DCBA-T2 using Natural Mo source plate of 45 mg/cm 2 thick Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 12

DCBA-T2 after installing Mo Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 13

Detection Efficiency for 2 νββ in DCBA-T2 Nat. Mo (10% 100 Mo) 45 mg/cm 2 0 kG All direction B=0.6 kG 0.6 kG All direction Back-to-back 0.6 kG Back-to-back ε = 9.5% Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 14

Back-to-back event of DCBA-T2 (Candidate of 2 νββ ) Time gap B = 0.8 kG 35 Anode wire number Wire pitch = 6 mm 30 0.6 MeV 25 0.3 MeV 20 Helical Radius: r Azimuth Angle: ϕ 15 Y 10 Natural Mo plate (10% 100 Mo) X 5 (45 mg/cm 2 ) 0 Pickup wire 5 X 10 15 cos λ =0.457 Pitch Angle: λ 20 25 Z 30 cos λ =0.985 35 FADC counts/10 ns Opening angle θ≈ 120 deg 10 µ sec ≈ 5 cm cos θ = − 0.5 090505-39_12 Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 15

Back-to-back event probably coming from 214 Bi Y 214 Bi (Uranium decay series) X e2=1.369 MeV r2=34.1 mm β max =1.85 MeV e1=0.342 MeV (e1=0.342 MeV) r1=23.9 mm 0 + 1.42 MeV 3.27 MeV cos λ 2 =0.452 conv. elec. cos λ 1 =0.839 (e2=1.369 MeV) X 0 + Z 214 Po Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 16

Background Event / Double Compton? T=0.32 MeV LY(-614, 28, Z) r=26.3 mm RY(621, 30, Z) r=21.1 mm T=1.14 MeV 12 mm X-Y plane RZ1(623, Y, 18) LZ(-626, Y, 20) cos λ =0.963 cos λ =0.321 RZ2(636,Y, 21) X-Z plane 10FADC counts ≈ 0.5 mm 090505-52_14 Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 17

DCBA-T3 (under construction) Geant4 976 keV ε≈ 52% 60 keV 2.4 kG Nd 2 O 3 40 mg/cm 2 5 cm 1500 keV Geant4 Refrigerator ε≈ 60% 80 keV 57 cm Nd 2 O 3 2.4 kG 40 mg/cm 2 57 cm SC-magnet Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 18

Differences between DCBA-T3 and T2 • Drift chamber Mini-jet chambers with multi-particle separation capability DCBA-T3 DCBA-T2 Source Nd 2 O 3 (40 mg/cm 2 × 13,760 cm 2 Nd 2 O 3 Natul. Mo:32g = 550 g : 150 Nd = 0.18 mol) 150 Nd = 0.008 mol 100 Mo=0.03 mol Sensitive vol. 8 × (4(X) × 44(Y) × 44(Z)) cm 3 9(X) × 26(Y) × 26(Z) cm 3 4 × (4(X) × 20(Y) × 44(Z)) cm 3 Anode pitch 3 mm 6 mm Pickup pitch 3 mm 6 mm Signal readout Flash ADC Flash ADC X-position Drift vel. × time : σ X ≈ 0.5 mm σ X ≈ 1 mm Y-position Anode position : σ Y ≈ 0.2 mm σ Y ≈ 0.2 mm Z-position Pickup position : σ Z ≈ 0.2 mm σ Z ≈ 0.2 mm • Magnet SC-solenoid + F.R.Y. Normal-sol.+ F.R.Y. Magnetic field 3.0 kG (Max.) 0.8 kG (Max) Uniform Vol. 80 dia. x 60 cm 3 δ B/B 0 < 1% 40 dia. x 60 cm 3 δ B/B 0 < 1% ∆ E/E expected at Q < 5% (FWHM) 6.3% (FWHM) Power consumption 1 kW (refri.)+10 W (power supply) 9 kW (Power supply) Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 19

DCBA-T3 Trigger Electronics and DAQ Chamber 4 Layers 1,280ch (1 st stage) Serial LVDS cable （ Digital transfer ） Start/Stop 32ch Pre-Amp & FADC module FPGA with Memory Trigger Board Magne CPU Board t EVENT Start MEMORY STOP Pickup FPGA Anode / 160ch Anode Pickup / 160ch DCBA-T3 DAQ Board CompactPCI Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 20

MTD (Magnetic Tracking Detector: temporary name) module after DCBA Chamber cell : the same as DCBA-T3, Source plate: 80 m 2 /module Thickness: 40 mg/cm 2 , Source weight: 32 kg/module Geant4 2.4 kG He+CO 2 (10%) 80 keV FWHM Nd 2 O 3 @ 1.7 MeV 40 mg/cm 2 0 1 2 3 Energy (MeV) 3500 = × FWHM ( E sum ) 2 80 keV ≈ 3 . 4 % Expected Energy Resolution Q ( 3370 keV ) Nd - 150 Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 21

Expected event rate in MTD Conditions < > • Assumed effective mass is 50 meV. m ββ • Used are from ν 0 T Faessler et al . presented at TAUP2009 1 / 2 and A. Staudt et al . in Europhys. Lett. 13 (1) (1990) 31. • 50 modules of MTD are operated. • Source thickness is 40 mg/cm 2 : thus 30 kg/mod × 50 mod = 1500 kg. • Event rate is obtained by ν n = ε 0 N ln 2 / T 0 1 / 2 where ε is the detection efficiency (=0.3) and N 0 the number of nuclei. Natural Nd 150 Nd 100 Mo 82 Se 76 Ge Source Item (5.6% 150 Nd) (60% enr.) (90% enr.) (90% enr.) (90% enr.) Amount (mol) 560 6000 13500 16460 17760 Faessler (y) 3.55 × 10 25 3.55 × 10 25 3.33 × 10 26 3.50 × 10 26 1.10 × 10 27 ν 0 T 1 / 2 Event rate (y − 1 ) 2 21 5 8 2 Staudt (y) 1.35 × 10 25 1.35 × 10 25 5.08 × 10 26 2.41 × 10 26 9.32 × 10 26 ν 0 T 1 / 2 Event rate (y − 1 ) 5 55 3 9 2 Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 22

DCBA collaboration DCBA N. Ishihara 1 , G. Iwai 1 , H. Iwase 1 , Y. Kato 1 , M. Kawai 1 , Y. Kondou, T. Haruyama 1 , T. Inagaki 1 , Y. Makida 1 , T. Ohama 1 , K. Takahashi 1 , S. Takeda 1 , Y. Yamada 1 , H. Igarashi 2 , T. Ishikawa 2 , T. Sumiyoshi 2 , E.Tashiro 3 , T. Ishizuka 3 , S. Kitamura 4 , Y. Teramoto 5 , I.Nakano 6 , Y. Sakamoto 7 , Y. Nagasaka 8 , N. Tamura 9 , K. Tanaka 10 , R. Ito 11 , 1 KEK, 2 TMU, 3 Shizuoka Univ., 4 NMS, 5 OCU, 6 Okayama Univ., 7 TGU, 8 HIT, 9 Niigata Univ., 10 SSI, 11 Futurescope (26 persons from 11 Institutes) Oct. 10-13, 2009 N. Ishihara at DBD09, Hawaii 23