Comparison of unfolding approaches for monoenergetic and continuous fast-neutron energy spectra

Deuterated scintillators and their application to neutron spectroscopy

“…Nuclear astrophysics reactions occur at very low bombardment energies and often result in low outgoing recoil particle energies. In the case of astrophysical reactions, which are often statistics limited, the MLEM algorithm provides an ideal method for unfolding since it accounts for the Poisson nature of the noise and counting statistics in a measurement [16]. A sample light-response spectrum with a low threshold setting for the 13 C(α,n) 16 O reaction at E α ¼ 7.5 MeV is shown in Fig.…”

“…A sample light-response spectrum with a low threshold setting for the 13 C(α,n) 16 O reaction at E α ¼ 7.5 MeV is shown in Fig. 7 with the 0 þ and 3 -states in 16 O labeled. Importantly, these states of interest are clearly identifiable from the light-response spectra alone, as shown in Fig.…”

“…There have been many algorithms developed for solving these types of inverse problems with organic scintillators [13][14][15][16][17][18]. The resulting neutron energy spectra obtained from spectrum unfolding is a probabilistic distribution of neutron counts per energy bin, thus one cannot directly correlate neutrons on an event-byevent basis without additional information.…”

“…One particularly attractive spectrum-unfolding algorithm pertaining to experimental nuclear physics measurements is the maximum-likelihood expectation maximization (MLEM) algorithm [16]. The MLEM method starts with defining a likelihood function for the process.…”

“…In the case of liquid scintillators, the likelihood function can be represented with a Poisson distribution. This representation is quite natural since it accounts for the Poisson nature of noise and photon counting statistics in the light-response spectra [16]. As derived in [16], the resulting iterative form of the MLEM algorithm take the form of Eq.…”