Observation of ground state of ⁴H in ³H(α,τt)n reaction
In kinematical complete investigation of ³H(α,τt)n reaction by using beam with Eα = 67.2 МеV and titan trituated target the ground state of ⁴Н was observed with Eg.s. = Ent = 3.22 ± 0.25 МеV and Г = 2.9 ± 1,1 МеV.
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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irk-123456789-805182015-04-19T03:02:53Z Observation of ground state of ⁴H in ³H(α,τt)n reaction Gorpinich, O.K. Povoroznyk, O.M. Jachmenjov, O.O. Ядерная физика и элементарные частицы In kinematical complete investigation of ³H(α,τt)n reaction by using beam with Eα = 67.2 МеV and titan trituated target the ground state of ⁴Н was observed with Eg.s. = Ent = 3.22 ± 0.25 МеV and Г = 2.9 ± 1,1 МеV. В кінематично повному дослідженні ³H(α,τt)n-реакції з використанням пучка альфа-частинок з енергією Еα = 67.2 МеВ і титан-тритієвої мішені спостерігався основний стан ядра ⁴Н з енергетичними параметрами Еeо.с. = Еnt = 3.22 ± 0.25 МеВ та Г = 2.9 ± 1.1 МеВ. В кинематически полном исследовании ³H(α,τt)n-реакции с использованием пучка альфа-частиц с энергией Eα = 67.2 МэВ и титан-тритиевой мишени наблюдалось основное состояние ядра ⁴Н с энергетическими параметрами: Eо.с. = Ent = 3.22 ± 0.25 МэВ и Г = 2.9 ± 1.1 МэВ. 2004 Article Observation of ground state of ⁴H in ³H(α,τt)n reaction / O.K. Gorpinich, O.M. Povoroznyk, O.O. Jachmenjov // Вопросы атомной науки и техники. — 2004. — № 5. — С. 31-34. — Бібліогр.: 21 назв. — англ. 1562-6016 PACS 24. 25.10.+s 25.55.-e 27.10.+h http://dspace.nbuv.gov.ua/handle/123456789/80518 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы |
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Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы Gorpinich, O.K. Povoroznyk, O.M. Jachmenjov, O.O. Observation of ground state of ⁴H in ³H(α,τt)n reaction Вопросы атомной науки и техники |
| description |
In kinematical complete investigation of ³H(α,τt)n reaction by using beam with Eα = 67.2 МеV and titan trituated target the ground state of ⁴Н was observed with Eg.s. = Ent = 3.22 ± 0.25 МеV and Г = 2.9 ± 1,1 МеV. |
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Article |
| author |
Gorpinich, O.K. Povoroznyk, O.M. Jachmenjov, O.O. |
| author_facet |
Gorpinich, O.K. Povoroznyk, O.M. Jachmenjov, O.O. |
| author_sort |
Gorpinich, O.K. |
| title |
Observation of ground state of ⁴H in ³H(α,τt)n reaction |
| title_short |
Observation of ground state of ⁴H in ³H(α,τt)n reaction |
| title_full |
Observation of ground state of ⁴H in ³H(α,τt)n reaction |
| title_fullStr |
Observation of ground state of ⁴H in ³H(α,τt)n reaction |
| title_full_unstemmed |
Observation of ground state of ⁴H in ³H(α,τt)n reaction |
| title_sort |
observation of ground state of ⁴h in ³h(α,τt)n reaction |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2004 |
| topic_facet |
Ядерная физика и элементарные частицы |
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http://dspace.nbuv.gov.ua/handle/123456789/80518 |
| citation_txt |
Observation of ground state of ⁴H in ³H(α,τt)n reaction / O.K. Gorpinich, O.M. Povoroznyk, O.O. Jachmenjov // Вопросы атомной науки и техники. — 2004. — № 5. — С. 31-34. — Бібліогр.: 21 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT gorpinichok observationofgroundstateof4hin3hattnreaction AT povoroznykom observationofgroundstateof4hin3hattnreaction AT jachmenjovoo observationofgroundstateof4hin3hattnreaction |
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2025-07-06T04:31:46Z |
| last_indexed |
2025-07-06T04:31:46Z |
| _version_ |
1836870593212841984 |
| fulltext |
OBSERVATION OF GROUND STATE OF 4H
IN 3H(α,τt)n REACTION
O.K. Gorpinich, O.M. Povoroznyk, O.O. Jachmenjov
Institute for Nuclear Research of Ukrainian Academy of Science, Kyiv, Ukraine
e-mail: orestpov@kinr.kiev.ua
In kinematical complete investigation of 3H(α,τt)n reaction by using beam with Eα = 67.2 МеV and titan
trituated target the ground state of 4Н was observed with Eg.s. = Ent = 3.22 ± 0.25 МеV and Г = 2.9 ± 1,1 МеV.
PACS 24. 25.10.+s 25.55.-e 27.10.+h
1. INTRODUCTION
The lightest nuclei which have excited levels are
few-nucleons systems with A = 4. Most of these states
are unbound and the only known particle stable state is
ground state of 4He [1]. There is enough experimental
evidence showing that 4Н and 4Li have only short living
particle unstable states. But obtained data on the energy
positions and widths of these states have often been
contradictory.
All numerous investigations of excited levels of 4H
[2-16] were indicated on it’s n+t structure. The most
contradictory are results of experiments on neutron
tritium interaction. For example energy dependence of
total cross section interaction neutrons with nuclei of
tritium shows strong resonance behavior at En ~
3.5 MeV [2]. In this time phase shift analysis [2] of
3H(n,n)3H data indicated that lowest T=1 levels of 4H
are broad resonances having assignments 2- and 1-,
resonance energies of 3.4 and 5.1 MeV, and equal
reduced widths of 5.4 MeV. However, this analysis was
questioned by publication [4]. Microscopic calculations
predict broad overlapping resonances at low excitation
energies of n+t system [5-6]. On the other hand in
different reaction measurements such as 7Li(π−,tt)n [7-
10] 6Li(π,dt)n [6-9], 4Hе(π,γ)tn, [11], 6Li(6Li,8B)tn [12],
7Li(τ,ττ,)tn [13], 7Li(n,αt)n [14], 3H(d,pt)n [15-16] and
2H(t,pt)n [17] was observed the only ground resonance
state of 4H. The values of 4H ground state energy as
obtained in this reactions range from 0.3 to 8 MeV in
the excitation energy in n+t system. The differences of
obtained values such as energy positions and energy
width could be explained by the complexity of studied
processes and experimental difficulties that
accompanied these investigations.
Additional source of information about energy
scheme and structure of excited levels of 4H may be
study of their occupation and different modes of decay
(on t+n and d+2n) by using α+t interaction at energy
that exceed threshold of decay of alpha-particle on two
deuterons. Then, investigating in kinematically
complete experiment 3Н(α,τt)n and 3Н(α,τd)2n
reactions may specify energy parameters of level
decayed on t+n by using the first, and by using the
second reaction to turn out if is it 4-particle resonance
formation with d+2n structure.
2. EXPERIMENT
Three-particle 3Н(α,τt)n reaction in kinematical
complete experiment with using triturated titan foils
with thickness 2.7 mg/cm2 and alpha-particle beam was
investigated on Kyiv isochronous cyclotron U-240. By
using time of flight technique, developed for
measurement of time and energy characteristics of
cyclotron’s beam was established that alpha-particle
beam’s energy in this experiment was equal
67.2 ± 0.4 MeV [18]. For identification and
determination energy of outgoing charge particles on
coincidence four ∆E-E telescopes were used. Two of
these, consisting of 400 µm Si ∆E-detector and ∅
20 mm×h 20mm NaJ(Tl) E-detector allocated for the
registration singly charged reaction products positioned
on one side to the beam’s direction(left arm) and other
two consisting of 90 µm Si ∆E-detector and 3 mm
Si(Li) E-detector assigned for registration of double
charged reaction products were situated on the other
side of the beam’s direction(right arm). Collimation of
telescopes was carried out by circular copper slits.
Diameter of slit is 6mm, distance from target to
telescopes situated on angle nearer to the beam’s
direction is 120 mm and 100 mm for telescopes situated
farther. Angular separation between two pairs of
telescopes situated as on the left arm and on the right
arm was 15 °. Coincidence between the pair of ∆E
detectors of telescopes which were purposed for
registration of single and double – charged reaction
products generated the event trigger for the acquisition.
The parameters of every event (amplitudes of analog
signals from each detectors, time lag between moments
of the registration of the particles in different pairs of
detectors, and the code of an event) were stored in the
form of the sequence of vectors for later analysis.
For carrying out the calibration were used binary
and three-particle reactions due to interaction of
incident alpha particles with 1Н, 2Н, 3Н, 12С nuclei. As
in the experiment were used NaJ(Ti) detectors which
response function depends on the type of charged
particles the methods of modeling of energetic
dependence of light output of scintillator from specific
ionization losses of the registered particle [19] and the
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2004, № 5.
Series: Nuclear Physics Investigations (44), p. 31-34. 31
empiric dependence of specific energetic losses of the
charged particles in the matter dE/dx ≈ En/a [20] were
worked out and used.
Different charged particles from 3H + 4He interaction
were identified in ∆E-E spectra, and selected τt
coincidences for each pair of telescopes were sorted into
(Eτ +∆Eτ) – (Et +∆Et) matrices by choosing windows on
the corresponding bit-pattern and the relevant time-to-
amplitude converter spectra
Fig. 1. Two-dimensional spectrum from3 Н(α,τt)n
reaction
Fig. 1 shows one of the τt coincidence matrix, where
solid line represent kinematic curve estimated for
correspondent geometric conditions of investigation of
the three-particle 3Н(α,τt)n reaction. Their arrangement
according to the experimental locus of coincidences
testifies the correctness of provided energy calibration.
3. DATA ANALYSIS
The obtained for different geometric conditions τt-
coincidence matrices were selected to look for
resonances in the n-t relative energy spectra
corresponding to the 4H state in the absent of resonances
of 4He and 6Li in corresponded relative τ-n and τ-t
energies. Some of the calculated dependencies of
relative energies of nτ, τt and tn outgoing pairs from the
energy detected τ-particles were represented on Fig. 2.
Dotted, dash and solid lines correspond to relative τ-t, τ-
n and t-n energies accordingly. The arrows directed to
the right axe to the right and to the left indicate the
energy position of resonance levels of 4He and 6Li,
correspondingly. The arrow directed to the left axe
indicate on magnitude energy of relative motion of
particles t and n equal 3 MeV, corresponded energy
position of ground state of 4H obtained in most of
experiment [12-16]. The levels of 4He were displayed
due to τ+n interaction, levels of 6Li due to τ+t. The
excitation energy Eex
4He(Eex
6Li) of nucleus 4He(6Li) is
related with kinetic energy Eτn(Eτt) of relative motion of
particles τ and n (τ and t) and energy Qdec4He(Qdec6Li)
available in the decay of ground state of 4He(6Li) into τ
+n (τ+t) channel by
( )
++−=
Lidec
tQHedec
nQtEnELi
exEHe
exE
6464
ττττ .(1)
The values of excitation energy of resonance of 4He
and 6Li labeled above of arrows were determined from
relation (1).
The most optimal conditions for the investigation of
formation and decay of resonance states of 4H in
excitation range from 2 MeV to 5 MeV carried out from
τt coincidences matrix at registration angles of τ-
particles - 27.5 ° and tritons – 15 °(see Fig. 2). Then
values of energy of relative motion in n+τ and τ+t
outgoing pairs don’t correspond to formations of
resonance levels in 4He and 6Li.
Fig. 2. The dependencies of relative motion of nτ, tτ
and tn outgoing pairs energy of detected τ-particle
The events of the upper branch of locus in two-
dimensional spectrum were projected on 3He energy axe
and had been additionally multiplied by inverse of its
phase space factor. The spectrum of relative n-t energy
was built in this way and is shown in Fig. 3.
The cross-section of three-body reaction 3H(α,τt)n
can be expressed by:
( ) ( ),,, ntEtifT
invexdEtdd
d ΩΩ=
ΩΩ τρπ
τ
σ 2423
(2)
where Tif is transition matrix element and ρ a density of
final states is three-body phase space factor, Ent (≡
Ent (Eex)) stands for the relative energy of particle n and t
corresponding to the excitation energy of the nucleus
(n+t) –4H and vin is the relative velocity in entrance
channel.
It will be assumed that process is sequential and
reaction proceeds in two steps. In the first step the
nucleus 4H is formed in state unstable to particle
emission 3H+α→τ+4H, which subsequently decays 4H→
t+n. The first step of the reaction can be treated as two-
body reaction and the matrix element of three-body
transition Tif
j can be expressed as multiplication of two
terms
32
( ) ( ) ( ),, ntEjXkjFntEkj
ifT = (3)
where first FJ(k) describes amplitude of formation of 4H
nucleus in state j and second term XJ(Ent) indicate it’s
decay in Breit-Wigner representation:
Fig. 3. The result of fitting procedure for upper
branch of τt- coincidence measurement. The solid line:
contribution of 4H ground state, dotted: of third excited
level of 4He
( ) ,
/iEE
/
EX
jntj
j
nt
j
2
2
Γ+−
Γ
= (4)
where Ent-energy of relative motion of neutron and
triton, Ej-energy position of resonance level, Γj-energy
width of resonance level.
For single wide resonance expression (2) turns into
( ) ( ) ( ) ,
/EE
/C
E,,
dEdd
d
jntj
jj
ntt
ext
22
3
2
2
Γ+−
Γ
=ΩΩ
ΩΩ τ
τ
ρσ
(5)
where Cj is the resonance constant.
The result of fitting procedure in frame of method of
least square with using expression (5) was represented
on Fig. 3 by solid line. Wide resonance abundance that
is observed in experiment is ground resonance state of
4H and obtained their energy parameters are the
following Ent = 3.22 ± 0.25 MeV; Γ = 2.93 ± 1.09 MeV.
The resonance structure which takes place in
spectrum (see Fig. 3)in range relative energies from 5 to
6.5 MeV is due to formation and decay on τ+n channel
of excited levels of 4He (see Fig. 2). The fitting
procedure carried out with using expression (5) for
excited levels of 4He is represented on Fig. 3 by dotted
line. This part of spectrum was described in assumption
that energy position of excited level of 4He is equal
21.5 ± 0.4 MeV and energy width Γ = 0.28 ± 0.27 MeV.
If to compare obtained energy parameters of excited
level 4He with represented in compilation paper [1]
scheme of 4He energy levels the value of energy
excitation with accounting experimental error is close to
energy position of the third excited 4He level
(E* = 21.84 MeV) but observed energy width is less (Γ
n = 0.75 MeV).
4. CONCLUSIONS
In our correlation experiment were created conditions
for investigation of the behavior of n+t interaction in
energy range of the relative energy of particle n and t
from 2 to 5 MeV. In this range of phase space we
observed resonance structure which corresponded
ground state of 4H. The results of analysis were
presented as on Fig. 3 and in table where for
comparison 4Н ground state parameters obtained from
others different correlation experiments were
represented too.
4Н ground state parameters obtained by correlation
experiments
Reaction ЕР, МeV Еtn, MeV Г, МeV
2H(t,pt)n[16] 35.3 3.1±0.3 2.1
7Li(n,αt)n[13] 14.6 2.6±0.4 2.1±0.3
3H(d,pt)n[14] 27.2 3.4±0.3 3.0±0.3
3H(d,pt)n[15] 47.3 2.2±0.4 3.4±1.2
3H(α,τt)n[*] 67.2 3.22±0.25 2.93±1.09
7Li(τ,ττ)tn[12] 120 2.6±0.4
Ep-energy of incident beam
[*] parameters obtained in this experiment
As one can see all these data agree quite well if one
takes in to account experimental errors. But the question
about the accordance between the results of
investigation of excitation of 4H only in n+t interaction
as for a example from measurements energy
dependence of total cross-section of n+t interaction or
energy dependencies phase shifts of elastic n+t
scattering and the results of correlation investigation is
remained. Represented in [1] results of analysis of direct
n+t interaction were indicated on complex scheme of
excited levels of 4H, on manifestation of some
resonance structure not only near Ent~3 MeV but at
Ent~5 and 6.5 MeV. In the same time presented in table
results of correlation experiments were limited by one
resonance ground state of 4H. Unfortunately as in our
correlation experiment and in others presented in table
one can’t investigate n+t interaction at Ent>5 MeV, But
for the solution of discrepancy problem it is necessary
to increase maximum value of investigated energy of
relative motion of n+t in correlation experiment to
8 MeV.
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НАБЛЮДЕНИЕ ОСНОВНОГО СОСТОЯНИЯ 4Н В 3H(α,τt)n-РЕАКЦИИ
О.К. Горпинич, О.М. Поворознык, А.А. Ячменёв
В кинематически полном исследовании 3H(α,τt)n-реакции с использованием пучка альфа-частиц с
энергией Eα = 67.2 МэВ и титан-тритиевой мишени наблюдалось основное состояние ядра 4Н с
энергетическими параметрами: Eо.с. = Ent = 3.22 ± 0.25 МэВ и Г = 2.9 ± 1.1 МэВ.
СПОСТЕРЕЖЕННЯ ОСНОВНОГО СТАНУ 4Н В 3H(α,τt)n-РЕАКЦІЇ
О.К. Горпинич, О.М. Поворозник, О.О. Ячменьов
В кінематично повному дослідженні 3H(α,τt)n-реакції з використанням пучка альфа-частинок з енергією
Еα = 67.2 МеВ і титан-тритієвої мішені спостерігався основний стан ядра 4Н з енергетичними параметрами
Еeо.с. = Еnt = 3.22 ± 0.25 МеВ та Г = 2.9 ± 1.1 МеВ.
34
Institute for Nuclear Research of Ukrainian Academy of Science, Kyiv, Ukraine
1. INTRODUCTION
2. EXPERIMENT
3. Data analysis
4. conclusionS
REFERENCES
О.К. Горпинич, О.М. Поворознык, А.А. Ячменёв
О.К. Горпинич, О.М. Поворозник, О.О. Ячменьов
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