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Mul i-nucleon ans e eac ions a ion ca che acili ies : a new way o p oduce and
s udy hea y neu on- ich nuclei
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Published e sion
Dickel, T.; Kankainen, Anu; Spa a u, A.; Amanbaye , D.; Beliuskina, Olga; Beck, S.;
Cons an in, P.; Benyamin, D.; Geissel, H.; G ö , L.; Ho nung, C.; Ka po , V.;
Ma do , I.; Munzenbe g, G.; Nichi a, D.; Plaß, W. R.; Pohjalainen, Ilkka;
Pu usho haman, S.; Reponen, Mikael; Ro a u, A.; Saiko, V. V.; Scheidenbe ge , C.;
Win ield, J. S.; Zad o nay, Alexand a; Supe -FRS Expe imen ; IGISOL
Collabo a ions
Dickel, T., Kankainen, Anu, Spa a u, A., Amanbaye , D., Beliuskina, Olga, Beck, S., Cons an in, P.,
Benyamin, D., Geissel, H., G ö , L., Ho nung, C., Ka po , V., Ma do , I., Munzenbe g, G., Nichi a,
D., Plaß, W. R., Pohjalainen, Ilkka, Pu usho haman, S., Reponen, Mikael, Ro a u, A., Saiko, V. V.,
Scheidenbe ge , C., Win ield, J. S., Zad o nay, Alexand a, Supe -FRS Expe imen , IGISOL
Collabo a ions. (2020). Mul i-nucleon ans e eac ions a ion ca che acili ies : a new way o
p oduce and s udy hea y neu on- ich nuclei. In NPA IX : 9 h Nuclea Physics in As ophysics
Con e ence (A icle 012012). Ins i u e o Physics. Jou nal o Physics : Con e ence Se ies, 1668.
h ps://doi.o g/10.1088/1742-6596/1668/1/012012
2020
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Mul i-nucleon ans e eac ions a ion ca che acili ies - a new way o
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Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
1
Mul i-nucleon ans e eac ions a ion ca che
acili ies - a new way o p oduce and s udy hea y
neu on- ich nuclei
T. Dickel1,2,A.Kankainen
3,A.Sp˘a a u2,4,5,D.Amanbaye
1,O.
Beliuskina3,S.Beck
1,2, P. Cons an in4,D.Benyamin
6,H.
Geissel1,2,L.G ¨o 1,C.Ho nung
1,A.V.Ka po
7,I.Ma do
6,8,
G. M¨unzenbe g2, D. Nichi a4,5,W.R.Plaß1,2, I. Pohjalainen3,
S. Pu usho haman2,M.Reponen
3, A. Ro a u4, V.V. Saiko7,
C. Scheidenbe ge 1,2,J.S.Winfield
2,A.Zad o naya
3and he
Supe -FRS Expe imen and IGISOL Collabo a ions
1II. Physikalisches Ins i u , Jus us-Liebig-Uni e si ¨a Gießen Gießen, Ge many
2GSI Helmhol zzen um ¨u Schwe ionen o schung GmbH, Da ms ad , Ge many
3Uni e si y o Jy ¨askyl¨a, Jy ¨askyl¨a, Finland
4Ex eme Ligh In as uc u e-Nuclea Physics, Ho ia Hulubei Na ional Ins i u e o
R&D in Physics and Nuclea Enginee ing, M˘agu ele, Romania
5Doc o al School in Enginee ing and Applica ions o Lase s and Accele a o s,
Uni e si y Poly echnica o Bucha es , Romania
6Tel A i Uni e si y, Tel A i , Is ael
7JINR, Dubna, Russia
8So eq Nuclea Resea ch Cen e , Ya ne, Is ael
E-mail: [email p o ec ed]
Oc obe 2019
Abs ac . The p oduc ion o e y neu on- ich nuclides hea ie han fission
agmen s is an ongoing expe imen al challenge. Mul i-nucleon ans e eac ions
(MNT) ha e been sugges ed as a me hod o p oduce hese nuclides. By he malizing
he eac ion p oduc s in gas-filled s opping cells, we can deli e hem as cooled high-
quali y beams o decay, lase and mass spec ome y expe imen s. High p ecision mass
spec ome y will allow o he fi s ime o uni e sally and unambiguously iden i y he
a omic and p o on numbe s o he ions p oduced in MNT eac ions. In his way hei
g ound and isome ic s a e p ope ies can be s udied in high-p ecision measu emen s.
In expe imen s a IGISOL, Finland and a FRS Ion Ca che , Ge many, we ha e
done and will pe o m b oadband measu emen s o he eac ion p oduc s, wi h he
aim o imp o e he unde s anding o he eac ion mechanism and o de e mine he
p ope ies o he g ound and isome ic s a es o he p oduced nuclides. Fi s esul s
and p epa a ions o upcoming expe imen s a e p esen ed.
Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
2
MNT eac ions a ion ca che acili ies
1. In oduc ion
Hea y neu on- ich nuclei play a key ole in he o ma ion o he hi d abundance peak
in he as ophysical apid neu on cap u e p ocess [1]. The p oduc ion, sepa a ion
and iden ifica ion o hese e y neu on- ich nuclides hea ie han fission agmen s
is a big expe imen al challenge, because o he con en ional me hods using s able
beams p e e ably p oduce neu on-deficien nuclei. Mul i-nucleon ans e (MNT), wi h
ene gies abo e he Coulomb ba ie , be ween medium-hea y o hea y beams and hea y
a ge s, ha e been sugges ed and in es iga ed as a possible al e na i e me hod [2, 3].
Radioac i e ion beams wi h ene gies a and sligh ly abo e he Coulomb ba ie open a
wide field o he s udy o MNT eac ions o hea y nuclei and hei applica ion o he
syn hesis o new exo ic hea y and supe hea y iso opes [4, 5, 6, 7]. Expe imen s in his
field can be di ided in h ee main g oups:
•S udy o MNT eac ions
•P oduc ion o in e es ing known iso opes and measu emen o hei p ope ies
(masses, hal -li es, isome s, e c.)
•P oduc ion o new exo ic iso opes and measu emen o hei p ope ies
Unde s anding he dis inc s eps o hese eac ions is manda o y o hei success ul
applica ion o he syn hesis o new iso opes. I will help o find op imum condi ions such
as p ojec ile- a ge combina ion and beam ene gy. Ou no el expe imen al app oach will
p o ide a new a enue o hese longs anding ques ions and will p o ide new expe imen al
da a needed o compa ison wi h calcula ions using diffe en heo e ical models [4, 8, 9].
Fig. 1 shows a compa ison o model and measu emen s o c oss-sec ions o a MNT
eac ion. As can been seen, i is sufficien o expe imen ally de e mine he o de o
magni ude o he c oss sec ion, i measu ed o e a la ge egion, o alida e a model.
Figu e 1. Compa ison o models and expe imen al da a o 238U+64Ni. Le
panel: GRAZING model[10]; Middle panel: Model o A. Ka po [11, 12]; Righ panel:
Measu emen s [13]. I can be clea ly seen ha he model o A. Ka po be e desc ibes
he measu ed da a.
The nuclides p oduced in MNT eac ions can be he malized in gas-filled s opping
cells as singly o doubly cha ged ions o allow o a as and efficien ex ac ion om he
s opping gas. They a e deli e ed as cooled high-quali y beams o decay, lase and mass
Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
3
MNT eac ions a ion ca che acili ies
spec ome y expe imen s [14, 15]. In his way hei g ound and isome ic s a e p ope ies
can be s udied in high p ecision measu emen s. The me hod has been pionee ed a he
KISS expe imen a RIKEN, Japan [16], whe e he p oduc s a e neu alized, ex ac ed
by he gas flow and hen e-ionized by lase ioniza ion. Expe imen s a IGISOL,
Finland and he FRS Ion Ca che , Ge many, ha e s a ed, wi h he aim o measu e
he g ound-s a e p ope ies o he eac ion p oduc s and o imp o e he unde s anding
o he eac ion mechanism i sel . In hese expe imen s p oduc ion c oss sec ion ( ela i e
o he elas ic c oss-sec ion o he beam o a ge ) and isome - o-g ound s a e a ios
can be measu ed. This in o ma ion can be used o alida e eac ion models and o
gain knowledge abou he spin and exci a ion ans e ed in he eac ion p ocess. We
desc ibe he e he wo expe imen s and ways o ob ain he in o ma ion abou he eac ion
p ocess.
2. MNT eac ion s udies wi h he FRS Ion Ca che
A he FRS [17] and he u u e Supe -FRS [18], a sys ema ic s udy o MNT eac ions
wi h exo ic ion beams will un eil he influence o a wide ange o p ojec ile isospin,
binding ene gy, de o ma ion as well as shell effec s. Beams om he FRS and he u u e
Supe -FRS could complemen eaccele a ed ones a ISOL acili ies, which a e limi ed in
ene gy and a ailabili y due o hei chemical p ope ies.
F om p e ious in es iga ions o MNT eac ions wi h s able beams i becomes
ob ious ha he p oduced nuclei shi owa ds he neu on- ich side o he cha o
nuclides wi h inc easing neu on numbe o he p ojec ile and a ge nuclei. The e o e,
neu on- ich in e media e-hea y and hea y adioac i e ion beams (RIBs) such as Xe
should lead o qui e neu on- ich ans e p oduc s. This may be he con en o
subsequen expe imen s a he (Supe -)FRS, ollowing he success o he cu en ly
scheduled expe imen on MNT s udies a he FRS [19].
As a fi s s ep, eac ions wi h slowed-down p ima y beams will be pe o med, as
an in e media e s ep owa ds eac ion wi h seconda y beams in he u u e. In his
expe imen in FAIR Phase-0, we will use a 238U p ima y beam (wi h abou 107ions
pe second) and 64Ni, 164Dy and 209Bi a ge s wi hin he exis ing C yogenic S opping
Cell (CSC) [20, 21] o he FRS Ion Ca che . In he nex gene a ion CSC o he Low-
Ene gy B anch o he Supe -FRS [22], he use o se e al a ge s in he s opping olume
will be possible (Fig. 2), he eby making op imal use o RIBs wi h hei b oad ene gy
and spa ial dis ibu ions and possibly cock ail beams. In bo h CSCs he low-ene gy
eac ion- esidues a e ex ac ed wi h high and almos elemen al independen efficiency
[19] and guided by RFQ sys ems o he high esolu ion mass spec ome e [23].
The iden ifica ion and coun ing is done ia p ecision mass measu emen s wi h a
MR-TOF-MS [23]. This me hod is uni e sal and applicable o all chemical elemen s.
In con as o o he me hods ha measu e he ionic cha ge o de e mine Z [13, 3] ou
me hod is no limi ed o ligh and medium-hea y nuclides. The e o e, we will p o ide
o he fi s ime unambiguous iden ifica ion o he hea y eac ion p oduc s. MR-TOF-

Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
4
MNT eac ions a ion ca che acili ies
MS can iden i y new iso opes independen o hei hal -li e (ms <T1/2<s able) and
also when hei decay scheme and nuclea s uc u e is no known. As a “by-p oduc ” o
a eac ion s udy he masses o all iden ified iso opes a e de e mined wi h high accu acy.
MR-TOF-MS can iden i y also long-li ed (>ms) isome s o hea y iso opes and de e mine
hei isome - o-g ound s a e a ios [24, 25]. Thus, new isome s can be disco e ed in MNT
eac ions and isome - o-g ound s a e a io can be used o in es iga e he spin ans e ed
in he ini ial p oduc ion mechanism. MR-TOF-MS can achie e simul aneously a high
esol ing powe and co e a b oad mass ange o abou 10% [25].









Figu e 2. The c yogenic chambe o he CSC o he FRS Ion Ca che . Inside he
chambe he a ge module wi h i s mo o d i en a ge wheel and new elec ode
s uc u e ha o ms he s opping olume o he MNT p oduc s is shown.
Fo hese expe imen s we ha e buil a sho e elec ode s uc u e and a ge module
o be ins alled inside he exis ing CSC. The change-o e be ween diffe en a ge s, i. e.
diffe en eac ions, will be as sho as one minu e due o a mo o -d i en a ge wheel
inside he CSC, see Fig. 2. The expe imen is simple and uni e sal as he c oss sec ions
o a ge -like agmen s (TLF) and p ojec ile-like agmen s (PLF) a e measu ed wi h
he same me hod in one expe imen , because ions o all agmen s a e s opped in he CSC
and a e ex ac ed essen ially independen o hei chemical na u e [19]. The c oss sec ion
measu emen s a e es ima ed o ha e an unce ain y o up o a ac o 2. Ne e heless, as
shown in Fig. 1 and in he li e a u e [26], an o de o magni ude is sufficien o alida e
eac ion models.
All pa s o he p ocess ha e been subjec o de ailed simula ion s udies, om he
eac ion in he a ge o he s opping o he ions in he gas (GEANT4 [27]) o he low
ene gy anspo in he CSC and he MR-TOF-MS (SIMION [28]). A simula ed mass
spec um o he ep esen a i e TLF egion o he beam o 238U on a ge 64Ni is shown
in Fig. 3.
In he fi s measu emen campaign we expec o measu e mo e han 150 c oss-
sec ions and abou 15 new masses. These will be in he a e-ea h egion, p o iding
mass da a impo an o unde s anding he o igin o he a e-ea h peak in he -p ocess
Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
5
MNT eac ions a ion ca che acili ies
3560 3565 3570 3575 3580
100
101
102
103
104
o (μs)
coun s
A=60 A=61
A=62
A=63
A=64
64Fe
64Cu
64Co
64Ni
104
103
102
101
100
3563.73563.4
Figu e 3. Simula ed high- esolu ion and b oadband mass spec um o MR-TOF-MS
measu emen o a ge -like agmen s o p ima y beam 238U on a ge 64Ni showing
he unambiguous iden ifica ion (A and Z) o he eac ion p oduc s wi h he MR-TOF-
MS. The ions a e singly cha ged.
abundances, and he fi s di ec mass measu emen s o neu on- ich ans-u anium
iso opes abo e A>238. Mo eo e , we expec o find se e al new isome ic s a es, since
MNT eac ions can be a e y powe ul me hod o his [29].
3. MNT eac ions expe imen s a IGISOL
The Uni e si y o Jy ¨askyl¨a has a he JYFL accele a o labo a o y a K130 hea y
ion cyclo on ha p o ides beams o se e al expe imen al acili ies. One o hem is
he IGISOL acili y, whe e eac ion p oduc s a e s opped in a gas-filled s opping cell,
ex ac ed by gas flow and a sex upole ion guide [30]. The p oduc s a e accele a ed
o 30 keV and mass-sepa a ed be o e hey a e deli e ed o diffe en measu emen s
s a ions shown in Fig.4. Yield measu emen s a IGISOL ha e been done, e.g. o
fission agmen s [31].
The fi s expe imen s ha used MNT eac ions a IGISOL ha e been done mo e
han a decade ago [32]. Howe e , hese ea ly expe imen s suffe ed om ela i ely low
efficiencies o he s opping cell and limi ed coun ing and iden ifica ion de ec ion sys ems.
Recen ly a dedica ed campaign has been s a ed o imp o e se e al aspec s, wi h he aim
o gaining o de s o magni ude in sensi i i y and es ablishing MNT eac ions as a new
eac ion ype o p oduce iso opes a IGISOL. The e ha e been nume ous upg ades o he
ion sou ce, accele a o and he IGISOL acili y in gene al. Fo he MNT expe imen s
Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
6
MNT eac ions a ion ca che acili ies
Figu e 4. Layou o he IGISOL acili y. A IGISOL a b oad ange o low-ene gy (30
keV) adioac i e and s able ion beams o s udies o a omic nuclei and hei p ope ies
[11,12] a e p oduced.
he new and flexible a ge module, he o-be-buil dedica ed s opping cell and he
newly ins alled MR-TOF-MS will be e y impo an . To op imize he yields and
condi ions, de ailed GEANT4 simula ions [33] ha e been done. To allow an easy and
as cha ac e iza ion o he se up in he s a -up phase, 209Bi a ge s a e used o p oduce
α-decaying iso opes, which a e as and easily iden ified wi hou mass selec ion. Such
an α-spec um measu ed du ing he fi s es expe imen can be seen in Fig. 5. The
de ec o was ins alled be o e he magne ic dipole, he e o e no mass sepa a ion was done
p io o de ec ion.
The inse shows he zoom on he p ominen alpha peaks om he g ound and
isome ic s a e o 211Po. As men ioned abo e he measu emen s o he isome ic- o-
g ound s a e a io can be used o be e unde s and he eac ion p ocess and he spin
and exci a ion o he nucleus be o e e apo a ion [34, 35]. A e he success ul es o he
209Bi a ge and he alpha-spec oscopy o he eac ion p oduc s a IGISOL, he same
will be used o he commissioning o he expe imen s a he FRS.
4. Conclusions
We p opose a no el me hod o eac ion s udies, which will pa e he way o b oad a ie y
o s udies wi h p ima y and seconda y beams. To ul ima ely p oduce exo ic nuclei which
a e no accessible by con en ional p oduc ion me hods. The concep is based on he
expe imen al se ups a IGISOL, Uni e si y o Jy ¨askyl¨a, Finland and a GSI/FAIR,
Nuclea Physics in As ophysics IX (NPA-IX)
Jou nal o Physics: Con e ence Se ies 1668 (2020) 012012
IOP Publishing
doi:10.1088/1742-6596/1668/1/012012
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MNT eac ions a ion ca che acili ies
Figu e 5. Alpha-decay om agmen s o p ima y beam o abou 10 pnA o 136Xe
a 945 MeV beam ene gy on a ge 209Bi ( hickness 5μm). By using high esolu ion
MR-TOF-MS in upcoming expe imen s a simila unambiguous iden ifica ion o decay
p oduc s independen on hei decay p ope ies will be possible.
Ge many. The CSC and he MR-TOF-MS ha e a wo ld-wide unique combina ion o
pe o mance pa ame e s ha a e needed o s op and measu e he eac ion p oduc s in
a uni e sal and efficien way. The measu ed masses will ha e an impo an inpu in
he unde s anding o he a e-ea h peak o he -p ocess and neu on- ich ac inides.
The sys ems a e complemen a y o each o he in many aspec s, a IGISOL addi ional
de ec ion me hods a e a ailable, such as lase and decay spec oscopy. Bu he sys em
a he FRS has highe efficiency and allows o also s udy hea y p ima y beams, e.g.
238U.
Acknowledgemen s
This wo k was suppo ed by he Eu opean Union’s Ho izon 2020 esea ch and inno a ion
p og am unde g an s No. 771036 (ERC CoG MAIDEN) and No. 654002 (ENSAR2),
he Ge man Fede al Minis y o Educa ion and Resea ch (BMBF) unde unde
con ac s no. 05P16RGFN1 and 05P19RGFN1, by Jus us-Liebig-Uni e si ¨a Gießen
and GSI unde he JLU-GSI s a egic Helmhol zpa ne ship ag eemen , by HGS-HIRe,
by he Hessian Minis y o Science and A (HMWK) h ough he LOEWE Cen e
HIC o FAIR, by he Romanian Minis y o Resea ch and Inno a ion unde esea ch
con ac PN 19 06 01 05, by he Is ael Minis y o Ene gy unde esea ch g an No.
217-11-023 and by RSF g an N0. 19-42-02014.