dc-squid current sensors for the readout of high-resolution Metallic Magnetic Calorimeters J. Beyer for MetroBeta consortium

Transcription

1 dc-squid current sensors for the readout of high-resolution Metallic Magnetic Calorimeters J. Beyer for MetroBeta consortium IWSSD AIST Tsukuba Nov 2016

2 The unit of activity - Bq - of b-emitters MMCs /SQUIDs for b-spectrometry - efficient magnetic flux transfer - readout noise contribution - parasitic thermal loading

3 Activity of b -emitters b - - emission Legal unit of Activity: Bq = s -1 continous electron energy spectrum S( E ), E: 0... E end presence of shell electrons affects S( E ) PM clicks / s scintillator-based methods established at NMIs for absolut activity measurements

4 Activity of b -emitters Liquid Scintillator Counting - TDCR b-emitter in scintillator solution S( E ), T/D, h absolute activity

5 241 Pu activity concentration / kbq g Pu activity co ncentration in kbq g Activity of b -emitters 2012 key comparison among NMIs: Pu identical TDCR data b-spectrum variied variation in sample activity up to 15 % assumed average β-energy E b(ave) / kev beta spectrum average e nergy in kev

6 MMCs for b -spectrometry talk MMC-I1: introduction to MMCs b-emitter 4p absorber MMC flux transformer coupled SQUID detector physics understood - noble metal absorbers: b -absorption and thermal properties at low T - MMC thermodynamics and magnetic properties (Au:Er, Ag:Er) very high energy resolution good (non-)linearity 4p absorber 100% QE - SQUID readout more difficult (e.g. TESs) - efficient magnetic flux transfer - readout noise contribution - parasitic thermal loading

7 MMCs for b -spectrometry requirements on SQUIDs for MMC readout B dm L MMC di MMC M IN = k L IN L SQ L IN L SQ optimal signal coupling: Φ = SQUID 1 2 k L L SQ MMC Φ MMC full enclosure in sufficiently thick absorber 100% b -absorption L MMC L IN, k 1 end point energy E b(max) 4 p absorber V Abs, C abs MMC B, L MMC kev nj/k L IN = nh nuclide E b(max) / kev Sm C Tc Cl-36 20mK

8 MMCs for b -spectrometry requirements on SQUIDs for MMC readout detailed MMC / SQUID readout modeling tolerable SQUID noise for acceptable degradation of energy resolution DE MMC e.g. S. Kempf et al. Supercond. Sci. Technol. 28 (2015) relevant parameter to quantify SQUID noise: coupled energy sensitivity e C = S F / 2L SQ / k 2

9 noise amplitude / a.u. MMCs for b -spectrometry requirements on SQUIDs for MMC readout schematic noise spectra MMC /SQUID setup total SQUID MMC frequency f / Hz

10 PTB SQUID sensors for MMCs integrated 2-stage SQUID cascades +FIN -FIN Z -IN +F -F +I +FX -IFX -V +V +IN double-trafo input XS: L IN 27 nh, k 0.6 S: L IN 65 nh, k 0.68 SQ1 output current feedback integrated SQ2: 16-SSA

11 3.3 mm PTB SQUID sensors for MMCs integrated 2-stage SQUID cascades input double- trafo SQ1 SQ1 bias resistor SQ2: 16-SSA

12 PTB SQUID sensors for MMCs typical noise performance coupled energy sensitivity e c / h 100 L IN 65 nh k 0.68 e c,w = 30 h 2-stage cascade with low-noise electronics, e.g. Magnicon XXF-1 operation temperature 300 mk L IN 27 nh k frequency f / Hz

13 MMCs for b -spectrometry requirements on SQUIDs for MMC readout detailed MMC / SQUID readout modeling tolerable SQUID noise for acceptable degradation of energy resolution DE MMC e.g. S. Kempf et al. Supercond. Sci. Technol. 28 (2015) kev DE MMC,theor ev max. resolving powers mk

14 PTB SQUID sensors for MMCs power dissipation T chip,min 200 mk SQ1 0.3nW heat-sinking pads SQ2: 16-SSA 3nW SQ1 bias resistor 1.5nW heat-sinking pads

15 PTB SQUID sensors for MMCs single SQUID front-ends +FIN -FIN Z -IN +F -F -V +V -V APF +IN double-trafo input XS: L IN 27 nh, k 0.6 S: L IN 65 nh, k 0.68 SQ1 output current feedback optional SQ1 bias resistor, SQ2 on separate chip

16 PTB SQUID sensors for MMCs single SQUID front-ends x10 less power dissipation on front-end chip

17 PTB SQUID sensors for MMCs single SQUID front-ends L MMC chip-to chip wire bonds 12.5 mm Al L para 2 nh optional heat-sinking chips L para 5 nh

18 Summary MMC-based b -spectrometry improved realization of unit Bq for pure b-emitters MetroBeta - 4 nuclides to be measured with unprecedented energy resolution SQUID current sensors for MetroBeta-MMCs - 2 input coil sizes for efficient magnetic flux transfer - readout noise and L para will practically not degrade DE MMC - non/integrated 2-stage cascades - optional low-inductance heat sinking chips for minimal parasitic thermal loading