Search for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> -delayed fission of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mi>Au</mml:mi> <mml:none/> <mml:mrow> <mml:mi>g

A search for a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mi>β</a:mi> </a:math> -delayed fission ( <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mrow> <b:mi>β</b:mi> <b:mi>DF</b:mi> </b:mrow> </b:math> ) decay branch of isomerically pure samples of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mmultiscripts> <c:mi>Au</c:mi> <c:none/> <c:mi>g</c:mi> <c:mprescripts/> <c:none/> <c:mn>178</c:mn> </c:mmultiscripts> </c:math> and <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mmultiscripts> <d:mi>Au</d:mi> <d:none/> <d:mi>m</d:mi> <d:mprescripts/> <d:none/> <d:mn>178</d:mn> </d:mmultiscripts> </d:math> was performed at the ISOLDE-CERN facility. Two complementary detection systems capable of registering <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mi>α</e:mi> </e:math> decays and fission fragments, the ISOLDE Decay Station and the ASET (Alpha SETup), were used. Despite very high statistics of produced <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mmultiscripts> <f:mi>Au</f:mi> <f:mprescripts/> <f:none/> <f:mn>178</f:mn> </f:mmultiscripts> </f:math> nuclei, no fission fragments were detected. Upper limits of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:mi>β</g:mi> <g:mi>DF</g:mi> </g:mrow> </g:math> probabilities of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"> <h:mrow> <h:msub> <h:mi>P</h:mi> <h:mrow> <h:mi>β</h:mi> <h:mi>DF</h:mi> </h:mrow> </h:msub> <h:mrow> <h:mo>(</h:mo> <h:mmultiscripts> <h:mi>Au</h:mi> <h:none/> <h:mi>g</h:mi> <h:mprescripts/> <h:none/> <h:mn>178</h:mn> </h:mmultiscripts> <h:mo>)</h:mo> </h:mrow> <h:mo>&lt;</h:mo> <h:mn>1.11</h:mn> <h:mrow> <h:mo>(</h:mo> <h:mn>2</h:mn> <h:mo>)</h:mo> </h:mrow> <h:mo>×</h:mo> <h:msup> <h:mn>10</h:mn> <h:mrow> <h:mo>−</h:mo> <h:mn>8</h:mn> </h:mrow> </h:msup> </h:mrow> </h:math> and <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"> <i:mrow> <i:msub> <i:mi>P</i:mi> <i:mrow> <i:mi>β</i:mi> <i:mi>DF</i:mi> </i:mrow> </i:msub> <i:mrow> <i:mo>(</i:mo> <i:mmultiscripts> <i:mi>Au</i:mi> <i:none/> <i:mi>m</i:mi> <i:mprescripts/> <i:none/> <i:mn>178</i:mn> </i:mmultiscripts> <i:mo>)</i:mo> </i:mrow> <i:mo>&lt;</i:mo> <i:mn>9.7</i:mn> <i:mrow> <i:mo>(</i:mo> <i:mn>2</i:mn> <i:mo>)</i:mo> </i:mrow> <i:mo>×</i:mo> <i:msup> <i:mn>10</i:mn> <i:mrow> <i:mo>−</i:mo> <i:mn>9</i:mn> </i:mrow> </i:msup> </i:mrow> </i:math> were determined. Corresponding lower limits of <j:math xmlns:j="http://www.w3.org/1998/Math/MathML"> <j:mrow> <j:mi>β</j:mi> <j:mi>DF</j:mi> </j:mrow> </j:math> partial half-lives were deduced as well, and the results are discussed in the context of experimental systematics of <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"> <k:mrow> <k:mi>β</k:mi> <k:mi>DF</k:mi> </k:mrow> </k:math> in the neutron-deficient region of the nuclear chart.