To obtain reaction rates in a wide temperature range 






T


9


=
0.001


–10 (where T9 is in units of 109 K) for BBN calculation inputs, continuous excitation functions over 






10


−
8




 to a few MeV are needed for numerical integration. Therefore we performed an R-matrix analysis to compile both the present and the previous data of these three reaction channels by using AZURE2 (Azuma et al. 2010) including all the relevant partial widths 






Γ


n




, 






Γ


p
0




, 






Γ


p
1




, and 






Γ


α




. The 7Be




(
n
,


p


0


)


 data set used for the R-matrix analysis is based on the same selection as used in Damone et al. (2018), Damone (2018; part of Dam18 + Sek76 as displayed in Figure 2), and the present THM data, Bor63, and Pop76 are added. For the 7Be




(
n
,


p


1


)


 and 7Be




(
n
,
α
)


 channels, all the labeled data shown in Figure 2 (except for p1 Tom19 and 




γ
α


 Bar16) were used without any data cutoff. Appendix B shows the adopted data sets more explicitly. We included nine known levels below the 8Be excitation energy of 






E


x


=
24

MeV


 (Tilley et al. 2004) and an additional nonresonant background pole, with a common channel radius of 5 fm for each channel in the same manner as Adahchour & Descouvemont (2003). The most significant channel 7Be






(
n
,


p


0


)


7




Li is dominated by four of these levels as described in detail by a former R-matrix study (Adahchour & Descouvemont 2003; Descouvemont et al. 2004); the 2− resonance near the neutron threshold (labeled as level I) principally dominates the cross section up to the BBN energies, the two 3+ states at 






E


x


=
19.24

MeV


 (level II) and 






E


x


=
21.5

MeV


 well characterize the corresponding single peaks, and a 2+ background pole accounts for the enhancement at high energies. The most important resonances to expand analysis to the 7Be






(
n
,


p


1


)


7




Li* and 7Be






(
n
,
α
)


4




He channels are the 1− state at 






E


x


=
19.4

MeV


 (level III) and the 2+ state at 






E


x


=
20.1

MeV


 (level IV), respectively; the former expresses the 7Be




(
n
,


p


1


)


 resonance behavior peaked at 






E


c
.
m
.


∼
0.5

MeV


 tailing down to the thermal neutron energy by the 




1

/

v


 law, and the latter forms the first peak in the 7Be




(
n
,
α
)


 spectrum around 






E


c
.
m
.


∼
1

MeV


. Despite its importance in the 




(
n
,
α
)


 channel, level IV is much less significant in the total cross section especially at lower energies due to its p-wave nature. Therefore we imposed some restrictions on level IV, which made the analysis much simpler; fixing 






Γ


p
0




, 






Γ


p
1




, and 






Γ


α




 at a known ratio 






Γ


α



/



Γ


p


∼
4.5


 (Tilley et al. 2004), and freeing 






Γ


n




 and resonance energy (refitted to be 19.87 MeV) not to significantly exceed the known total width 




Γ
=
880


keV


 (Tilley et al. 2004). The other four higher-lying levels (0+ at 






E


x


=
20.2

MeV


, 2+ at 






E


x


=
22.24

MeV


, 1− at 






E


x


=
22


 MeV, and 2− at 






E


x


=
24


 MeV) play rather supplementary roles mainly for the higher-energy behavior. The 4+ and 4− higher-spin states (at 






E


x


=
19.86

MeV


 and 20.9 MeV, respectively) were not included due to their limited influences. We do not introduce the γ-emission channels to fit the Bar16 plots (representing the 7Be








n
,
γ
α




4




He reaction channel Barbagallo et al. 2016), which appears significant only below the BBN energies. See Appendix C for more details on the present R-matrix analysis.
Citation: Tilley et al. 2004
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Citation: Tilley et al. 2004
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Citation: Tilley et al. 2004
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Citation: Descouvemont et al. 2004
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