Editing Tetraneutron (section)

== Marqués' experiment ==
[[Francisco-Miguel Marques|Francisco-Miguel Marqués]] and co-workers at the [[Grand Accélérateur National d'Ions Lourds|GANIL]] accelerator in [[Caen]] used a [[particle accelerator]] to fire atomic nuclei at carbon targets and observed the "spray" of particles from the resulting collisions.<ref>{{Cite journal |last1=Marqués |first1=F. Miguel |last2=Carbonell |first2=Jaume |date=March 2021 |title=The quest for light multineutron systems |url=https://link.springer.com/10.1140/epja/s10050-021-00417-8 |journal=The European Physical Journal A |language=en |volume=57 |issue=3 |page=105 |doi=10.1140/epja/s10050-021-00417-8 |issn=1434-6001|arxiv=2102.10879 |bibcode=2021EPJA...57..105M |s2cid=231986449 }}</ref> In this case the experiment involved firing [[beryllium-14]], [[boron-15]] and [[lithium-11]] nuclei at a small [[carbon]] target, the most successful being beryllium-14. This isotope of beryllium has a [[nuclear halo]] that consists of four clustered neutrons; this allows it to be easily separated intact in the high-speed collision with the carbon target.<ref name="marques02">{{Cite journal |last1=Marqués |first1=F. M. |last2=Labiche |first2=M. |last3=Orr |first3=N. A. |last4=Angélique |first4=J. C. |last5=Axelsson |first5=L. |last6=Benoit |first6=B. |last7=Bergmann |first7=U. C. |last8=Borge |first8=M. J. G. |last9=Catford |first9=W. N. |last10=Chappell |first10=S. P. G. |last11=Clarke |first11=N. M. |last12=Costa |first12=G. |last13=Curtis |first13=N. |last14=D’Arrigo |first14=A. |last15=de Góes Brennand |first15=E. |date=2002-04-01 |title=Detection of neutron clusters |url=https://link.aps.org/doi/10.1103/PhysRevC.65.044006 |journal=Physical Review C |language=en |volume=65 |issue=4 |page=044006 |doi=10.1103/PhysRevC.65.044006 |issn=0556-2813|arxiv=nucl-ex/0111001 |bibcode=2002PhRvC..65d4006M |s2cid=37431352 }}</ref> Current nuclear models suggest that four separate neutrons should result when [[beryllium-10]] is produced, but the single signal detected in the production of beryllium-10 suggested a multineutron cluster in the breakup products; most likely a beryllium-10 nucleus and four neutrons fused together into a tetraneutron.

A later analysis of the method used in the Marqués' experiment suggested that the detection mechanism was unlikely<ref name="sherrill04">{{cite journal
 | last1 = Sherrill | first1 = B. M. 
 | last2 = Bertulani | first2= C. A
 | year = 2004
 | title = Proton-tetraneutron elastic scattering
 | journal = [[Physical Review C]]
 | volume = 69 | issue = 2 | pages = 027601
 | doi = 10.1103/PhysRevC.69.027601
 | arxiv = nucl-th/0312110 |bibcode = 2004PhRvC..69b7601S | s2cid = 26590179 
}}</ref> but the suggestion was refuted,<ref name="marques05">{{cite arXiv
 | last = Marqués | first = F. M. 
 | display-authors= etal 
 | year = 2005
 | title = On the possible detection of <sup>4</sup>n events in the breakup of <sup>14</sup>Be
 |eprint = nucl-ex/0504009v1 
}}</ref> and attempts to reproduce these observations with different methods have not successfully detected any neutron clusters.<ref name="aleksandrov05">{{cite journal
 | last = Aleksandrov | first = D. V.
 | display-authors= etal 
 | year = 2005
 | title = Search for Resonances in the Three- and Four-Neutron Systems in the <sup>7</sup>Li (<sup>7</sup>Li, <sup>11</sup>C) 3''n'' and <sup>7</sup>Li (<sup>7</sup>Li, <sup>10</sup>C) 4''n'' Reactions
 | journal = [[JETP Letters]]
 | volume = 81 | issue = 2 | pages = 43–46
 | doi = 10.1134/1.1887912
 | bibcode = 2005JETPL..81...43A 
 | s2cid = 121267804
}}</ref>