210Pb Properties

Harry Nelson10/9/05

Basic ideas were pursued by Rick G. and Jip starting in 2002: seehttp://cdms.brown.edu/cdms_restricted/backgrounds/montecarlo/GEANT4/demos/Radioactive_BG/and files in that directory prefixed 210Pb_***.

This talk contains some of the plots from the literature on the 210Pb decay complex.See also http://hep.ucsb.edu/people/hnn/backgroundmeeting/pb210.pdf

Implantation222Radon 218Polonium+α 214Pb(Lead)+α

Τ1/2= 3.8 days 186 seconds 27 minutes 214Pb(Lead) 214Bismuth+β− 214Po+β−

Τ1/2= 27 minutes 20 minutes 164 μs 214Po 210Pb + α

↨146 keV

material

210Pb

dmax

dmax= 50±11 nm Aluminum35±12 Germanium58±12 Silicon13± 7 Tungsten

8-30 μm

SRIM:

Endpoint 63.6 keV B.R. 16±3%2 measurements, 1956-7 Quality not great

210Pb β− decay 210Pb22 yr

210Bi*

210Bi

Endpoint 16.96 keV B.R. 84±3% Measurement OK

210Pb β− decay spectra

Jaffe & Cohen, Phys. Rev 89, 454 (1952)

Huster, Phys. Rev 92, 1076 (1953)Pb(CH3)4 vapor in proportional chamberFluorescent X-rays escapeβ−

β−

+ Internal Conversions

High Energy β− branch hard to see…

210Pb High Energy β− decay Stanner & Ross, Proc. Phys. Soc. Lond. A 69, 836 (1956)Emulsion, tagged by Bismuth beta decay

These bins analyzed to estimate High Energy β− branch

L2L1

210Bi* decay: mostly Internal Conversion 210Bi*<3 ns

210Bi

46.539 keV4.25±0.04%

ToIL3

e-

33.12 keV0.50±0.02%

e-

30.83 keV6.0±0.2%

e-

30.15 keV57±2%

Per 210Pb decay

Campbell, J. Phys. A 36, 3219 (2003) Literature Review

24.6±0.8% emitFlourescent x-rays

M

e-

42.6 keV16±5%

N

e-

45.7 keV4.3±1.4%

NOP…

e-

46 keV0.9±0.3%

Mostly Augerelectron emission

Nucl. Data Tables A4, 1 (1968)Nucl. Data Tables A6, 235 (1969)Nucl. Data Tables A9, 119 (1971)Atom. Data. Nucl. Data Tables A81, 1, (2002).

Internal Conversion e- Spectrum (1)

Wu, Boehm, Nagel, Phys. Rev. 91, 319 (1953)

Only measurement I’veFound of M,N,O conversions

Internal Conversion e- Spectrum (2)

Gelletly & Geiger, Nucl. Phys.A123, 369 (1969)

A discrepancy`Missing’ Branching ratio:

From Internal Conversion Coefficients: BR()=5.24±0.18% (note, for *relative* IC rates, data and theory agree well)

Measurement (1990): BR()=4.25±0.04%

Perhaps /electron relative normalization is difficult.

Flourescent 210Bi x-raysCampbell, J. Phys. A 36, 3219 (2003)SiLi Detector

L3L3L3

NNNN

Table of Isotopes

Balance of energy: soft Auger electrons from M and N shell relaxation.

Subsequent Decays210Bismuth 210Polonium+β− 206Pb(Lead)+α

Τ1/2= 5.0 days 138 days Stable 1.16 MeV endpoint 5.3 MeV

210Bismuth beta decay has distorted spectrum,giving more low energy betas relative to higher energy betas than a simple Fermi spectrum. (line at left should be *straight*).

Plassman & Langer, Phys. Rev. 96, 1593 (1954)