Ultimate Hadron-Beam Brightness

I.FAST
Inno a ion Fos e ing in Accele a o Science and Technolog y
Ho izon 2020 Resea ch In as uc u es GA n° 101004730
MILESTONE REPORT
ULTIMATE HADRON-BEAM BRIGHTNESS
MILESTONE: MS19
Documen iden i ie :
IFAST-MS19
Due da e o deli e able:
End o Mon h 1 (Sep embe 2025)
Repo elease da e:
30/09/2025
Wo k package:
WP5: SMART, Task 2: PAF
Lead bene icia y:
CERN
Documen s a us:
Final
ABSTRACT
The ac i i y o Task 5.2 “Pushing Accele a o F on ie s” (PAF) suppo s he communi y e o in
pushing he had on-beam b igh ness. B igh had on beams a e undamen al o a omic and nuclea
physics expe imen s as well as o achie ing no el ul a-p ecise nuclea clocks (HITHOR). Mul i-
species beams in s o age ings a e o eseen as a no el in iguing possibili y o collisions in a
mo ing ame, and new insigh s in o nuclea eac ions. Space-cha ge o ces and in a-beam
sca e ing a e wo undamen al mechanisms ha limi he ul ima e beam b igh ness. Pushing
Accele a o F on ie s has co-o ganized he “Space Cha ge 2024” wo kshop whe e he s a e o he
a in his domain has been e iewed.
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I.FAST Conso ium, 2025
Fo mo e in o ma ion on IFAST, i s pa ne s, and con ibu o s, please see h ps://i as -p ojec .eu/
This p ojec has ecei ed unding om he Eu opean Union’s Ho izon 2020 Resea ch and Inno a ion p og amme unde
G an Ag eemen No 101004730. IFAST began in May 2021 and will un o 4 yea s.
Deli e y Slip
Name
Pa ne
Da e
Au ho ed by
G. F anche i, F. Zimme mann
GSI, CERN
30/09/2025
Re iewed
by
M. V e ena [on behal o S ee ing Commi ee]
CERN
30/09/2025
App o ed
by
S ee ing Commi ee
30/09/2025
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TABLE OF CONTENTS
1 Execu i e summa y ..................................................................................................................... 4
2 B igh ness limi a ions o had on beams..................................................................................... 4
3 Cohe en and incohe en e ec s o space cha ge ...................................................................... 5
4 Collec i e e ec s ........................................................................................................................ 10
5 In abeam Sca e ing and mi iga ion measu es: beam cooling .............................................. 11
5.1 Elec on Cooling ........................................................................................................................... 12
5.2 S ochas ic cooling ......................................................................................................................... 15
5.3 Ad anced schemes ........................................................................................................................ 16
6 The pa h owa ds he ul ima e b igh ness ................................................................................ 18
7 Conclusion ................................................................................................................................. 19
8 Re e ences ................................................................................................................................. 20
9 Annex: Glossa y ........................................................................................................................ 21
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1 Execu i e summa y
This epo ocuses on he esul s o he Space Cha ge Wo kshop held in Dongguan and on ongoing
ini ia i es aimed a achie ing ul ima e had on-beam b igh ness. The demand o highe -b igh ness
had on beams spans se e al key acili ies, including he s o age ings a GSI (ESR, CRYRING), he
u u e HESR ing a FAIR, CERN's accele a o complex (LEIR, PSB, PS, SPS, LHC), and he
Lanzhou ings a he IMP acili y in China. CERN also ope a es he AD and ELENA ings o low-
ene gy an ip o ons, while he HIAF p ojec in China plans cons uc ing he SR ing o s o ing exo ic
beams. P oducing high-b igh ness beams in hese exis ing and u u e accele a o s p esen s
signi ican challenges, including limi a ions om la ice s uc u es, beam in ensi y, in abeam
sca e ing (IBS), and collec i e e ec s. B igh ness can be enhanced h ough ad anced injec ion
echniques—such as wo o h ee-plane injec ion schemes (HIAF, GSI)—while space cha ge and
esonance e ec s a e being managed ia la ice op imiza ion and space-cha ge compensa ion
s a egies (e.g., a J-PARC). Collec i e e ec s a e mi iga ed using ch oma ici y con ol and eedback
sys ems. Emi ance g ow h due o IBS is add essed h ough ac i e beam cooling echniques, including
elec on, s ochas ic, and lase cooling, implemen ed in accele a o acili ies a GSI, CERN, and
HIAF. The epo also highligh s he global deploymen o hese echnologies. Addi ionally, we ske ch
he p og ess on ad anced concep s such as op ical s ochas ic cooling, cu en ly es ed a Fe milab’s
IOTA acili y, and lase cooling de elopmen s a GSI. Finally, we conclude wi h a discussion o he
oadmap owa ds achie ing he ul ima e beam b igh ness.
2 B igh ness limi a ions o had on beams
The ul ima e goal o had on beam p oduc ion is o b ing ions in o collision wi h a ixed a ge o wi h
ano he beam. A high-b igh ness beam is connec ed o luminosi y, and he highe he luminosi y, he
mo e collisions occu . B igh ness is de ined as he beam cu en “I” di ided by he 4D phase space
olume occupied by he beam. The e o e, a high-b igh ness beam equi es a la ge beam cu en in a
small phase space olume. P oducing high-b igh ness beams is challenging mainly due o he
epulsi e Coulomb o ce among he had on pa icles. The elec ic ields c ea ed by many pa icles
gene a e a space-cha ge e ec ha opposes he ocusing o ces o he accele a o . This e ec includes
bo h incohe en and cohe en esponses. The una oidable nonlinea i ies o he accele a o couple wi h
he space cha ge, causing ei he a apid cohe en beam esponse o a slow incohe en inc ease in
emi ance, due o he in e ac ion be ween ampli ude-dependen de uning and magne e o esonances.
These mechanisms complica e he p oduc ion o a high-densi y beam and hinde main aining i o e
ime wi hou special mi iga ion echniques.
Coulomb o ces o igina e om poin -like cha ged pa icles. Du ing beam p oduc ion, c ea ing small
phase space olumes ine i ably inc eases he beam's in insic collisionali y wi h o he pa icles—a
p ocess known as in abeam sca e ing (IBS). This undamen al p ocess esul s in Coulomb collisions
ha exchange ene gy and momen um among pa icles, ans e ing po en ial and kine ic ene gies
wi hin di e en pa s o he phase space. O e ime, IBS causes emi ance g ow h o "hea ing," which
educes he beam's b igh ness. Wi hou cooling echniques, achie ing ul ima e b igh ness is
impossible.
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The ansi ion om in abeam sca e ing be ween indi idual ion pai s and ion mo ion in he coa se-
g ained Coulomb po en ial o he pa icle ensemble is no cap u ed by mos o he accele a o
simula ion codes o he co esponding analy ical desc ip ions.
Fo physics based on s o age ings, he ul ima e b igh ness is o he main ac o s in he global scena io
a e he s o age ings o GSI (ESR, CRYRING), along wi h he u u e HESR pa o he FAIR plan,
he ings a CERN (LEIR, PSB, PS, SPS, LHC) as well as he IMP China acili y wi h he Lanzhou
s o age ings. CERN also ea u es he AD and ELENA wi h an ip o ons a low ene gy. In addi ion,
he HIAF p ojec in China o esees he cons uc ion o he SR ing o he s o age o exo ic beams.
Because o he b oad and join in e es o bo h IMP and IHEP in China, and also he “Helmhol z
Fo schungsakademie ü FAIR” (HFHF), he Pushing Accele a o F on ie s ask o iFAST co-
o ganized, in Sep embe 2024, he in e na ional Space Cha ge 2024 wo kshop in Dongguan, China.
3 Cohe en and incohe en e ec s o space cha ge
A HIAF, i is planned o deli e in ense beams o a ge s. The SRing will be ealized h ough linac
accele a ion and wo-plane injec ion in o he B ing [1]. The design in ensi y is 2.0 × 10^11 ppp, which
will be accele a ed in a cu ing-edge acili y wi h a as - amping a e o 12 T/s and a high epe i ion
a e o 3-5 Hz. The beam will be longi udinally s acked when ans e ing om he B ing o SRing.
In hese ings, he e ec o he incohe en space cha ge in he p esence o la ice nonlinea i ies is
c i ical, especially in iew o he po en ial 4 h-o de s uc u e esonances d i en by space cha ge in
he B ing, as is illus a ed in Fig. 1
Fig.1. Fou h-o de s uc u e esonances p edic ed by he CISP simula ion o he HIAF B ing [1].
The s a egy o mi iga ing he space cha ge e ec is o employ a high, as amping mode, 12T/s,
±38,000 A/s, wi h a peak powe o ±230 MW a ull load, elying on new echnology based on a MA
(Magne ic alloy) RF sys em [1], as is illus a ed in Fig. 2.

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Fig.2. Schema ic o he concep and ne wo k implemen a ion o he MA co e o he HIAF BRing [1].
A JPARC, he RCS elies on he H- mul i u n injec ion. This machine is highly space-cha ge
domina ed, which poses a se ious obs acle o ul illing mul iple demands simul aneously. Rou ine
ope a ion wi h 1 MW has s a ed a he MLF since Ap il 2024. The space cha ge and esonance e ec s
complica e simul aneous beam op imiza ions a high in ensi ies. Sys ema ic beam s udies and
nume ical simula ions a e conduc ed o he op imisa ion o many pa ame e s and hei pulse-by-
pulse swi ching o minimise beam loss and beam emi ance a bo h he RCS/MLF and he MR. The
incohe en space cha ge unesp ead is ~0.5, and his la ge a sp ead leads o an o e lap wi h impo an
machine esonances, leading o beam deg ada ion and beam loss. The majo esonances in he RCS
a e
1) Qx – 2Qy = -6, which is a s uc u e esonance exci ed by he sex upole ield componen in insic
o he bending magne s (BMs): K2 = 0.1006 m-2 (1/4 s eng h o ull x co ec ion). This esonance
a ec s ope a ion a lowe beam ene gies due o he la ge une sp ead. I also p oduces la ge
emi ance g ow h in he e ical plane. Fo he MLF beam, his esonance is co ec ed by
sex upoles, as he la e a e no being used o ch oma ici y co ec ion.
2) 3Qx = 19 is a 3 d o de andom esonance exci ed by he no -cancelled sex upole ield componen
(K2 = 0.0012 m-2) in he injec ion chicane magne s (SB). This esonance causes ho izon al
emi ance g ow h when he SBs a e ON du ing he beam injec ion. The e ec can be pa ially
mi iga ed by educing he magne ic ields o he SB by 20%.
3) Qx + 2Qy = 19 is a 3 d o de andom esonance ha a ises om he sex upole ields in he BMs
and ch oma ic co ec ion sex upole magne s. I is also addi ionally exci ed by a dis o ion o he
la ice supe -pe iodici y due o a be a bea ing caused by he chicane du ing injec ion. I leads o
wice la ge emi ance g ow h in he e ical plane. Cu en ly,  ~ 10% as Qy is se a om
he Qy = 6.5, and he bea ing is u he dec eased by educing SB ields.
4) The Mon ague esonance 2Qx-2Qy = 0 is a 4 h-o de sys ema ic esonance exci ed by skew-
quad upole e o s, he 2nd-o de e ec o he sex upola ield, and also by he oc upole componen
in he space cha ge ield. I is c i ical when Qx and Qy a e close o each o he . This esonance
causes an emi ance exchange be ween he ho izon al and e ical planes. I s e ec is mi iga ed
wi h a ca e ul choice o injec ion pain ing. The an i-co ela ed pain ing is a ou able o a la ge
ans e se pain ing [2].
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The 3-GeV RCS o J-PARC shows ha he space cha ge e ec a injec ion ene gy exci es many
esonances, esul ing in beam emi ance g ow h and beam losses. Beam handling, machine p ope ies,
and e o s ha e been inco po a ed in o he simula ions in o de o ob ain p ecise esul s, allowing he
iden i ica ion o each esonance e ec and de eloping he co esponding coun e measu es. Recen ly,
he SC e ec has been su icien ly mi iga ed a 1 MW ope a ion by combining se e al app op ia e
measu es. The beam loss and he beam emi ance ha e been minimized. The esidual beam loss o 1
MW is <<0.1% and his loss occu s almos en i ely du ing he injec ion pe iod, whe e abou hal o
he o al loss is a ibu ed o he oil sca e ing. The beam loss powe a he collima o is ~0.1 kW
(small compa ed wi h he collima o capaci y o 4 kW). The simula ion esul s a e well consis en
wi h he measu emen s. Imp o emen s o he RCS beam quali y ha e also been well ecognized a
he downs eam acili ies. The machine ac i a ion is well supp essed, achie ing a sus ainable
ope a ion wi h mo e han 98% a ailabili y.
Ano he impo an ask o each a high-b igh ness beam is he injec ion. The de elopmen o an
e icien me hod o accumula e as much beam as possible is necessa y. The s anda d app oach o
injec a had on beam om a linac in o a synch o on is ia a mul i- u n injec ion. This app oach is
usually implemen ed in one plane and equi es he c ea ion o a local bump o ill he ho izon al phase
space up o he machine accep ance. Fo p o on and ion mul i u n injec ion ia magne ic o
elec os a ic sep um, Liou ille’s heo em applies and se e ely es ic s he numbe o u ns, ypically
o ~15 u ns o single plane injec ion wi h op imized condi ions. The speci ic esul s depend on he
machine accep ance and he emi ance o he injec ed beam coming om he linac. To inc ease he
b igh ness also he e ical plane can be exploi ed, inc easing he numbe o injec ed u ns o ~100.
A HIAF, he wo-plane injec ion scheme is s udied and will be implemen ed o he BRing [3]. They
es ima e a 20% beam loss o e 100 u n injec ion o achie e a s able in ensi y o 1.3x1010 pa icles.
Figu e 3 shows a simula ion o he ull p ocess.
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Fig. 3. Two-plane injec ion a HIAF om a mul ipa icle simula ion ob ained ia CISP-GPU [3].
A GSI, he demand o inc easing he b igh ness is also pushing he s udies o he implemen a ion
o he wo-plane injec ion, as is illus a ed in Fig. 4.
In gene al, ho izon al-longi udinal and h ee-dimensional x-y-z injec ion schemes a e also easible.
These can be implemen ed wi h a nonze o dispe sion a he injec ion poin by a ying he beam ene gy
om he linac.
Fig. 4. Cha ac e is ic e iciency o he s anda d mul i u n injec ion. [4]. Two-plane injec ion s udies a GSI [5]; he s udy
shows he dependence o a wo-plane injec ion scheme e iciency as a unc ion o he machine wo king poin .
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A CERN, he LHC Injec o Upg ade g ea ly inc eased he beam b igh ness and pushed he in ensi y.
The space cha ge o ce is limi ing he emi ance in he PSB, he PS, and in he SPS, as is illus a ed
in Fig. 5. Resonance c ossing is he mechanism behind beam loss o emi ance g ow h caused by
space cha ge in all hese machines. In PS and SPS, he space cha ge condi ion is applied in he o m
Qy <0.31, 0.21, espec i ely. These limi s we e ound empi ically. Ideally, hey should bo h be nea
0.25 (i.e. he space a ailable be ween he 0.25 and in ege esonances), bu due o unce ain y in he
beam dis ibu ions and wid h o he s op bands, plus possible in luence om o he esonance lines
(e.g., he coupling esonance line) he alues chosen seem o be e ep esen he ac ual limi s in he
wo accele a o s unde some simpli ied assump ions.
In Fig. 5, he ounded shape o he cu es app oaches ze o, ollowed by a linea beha iou is because
o e y low emi ances he dispe si e pa o he beam ans e se size domina es, while o la ge
emi ances i is he emi ance pa . PS and SPS ha e bo h bunch- o-bucke injec ion. On he o he
hand, in he PSB, he beam is injec ed by H- cha ge exchange and chopped longi udinally om Linac4
o e se e al u ns. The “b igh ness line” shown is he bes line ha can be measu ed, and i also
oughly i s he simula ion o he injec ion p ocess. In eali y, he line should educe i s slope o low
in ensi ies (when he emi ance blow-up becomes domina ed by he sca e ing on he s ipping oil)
and e en ually le el o o 0.4 m e en o he limi o ze o in ensi y (because his is he emi ance
om Linac4). This is indica ed by he g een cu e in Fig. 5.
The so-called 8b4e bunch pa e n, consis ing o ains o 8 bunches spaced by 25 ns, ollowed by 4
“emp y” 25-ns bucke s, is limi ed by space cha ge in he SPS and, he e o e, is expec ed o pe o m
exac ly like he bunch comp ession, me ging, and spli ing (“BCMS”) scheme.
In mid-Augus 2025, a no malised ms emi ance o ≤1.5 m was measu ed a PS ex ac ion wi h
2.6×1011 p o ons pe bunch ex ac ed, consis en wi h he diag am, and also wi h measu emen s igh
a SPS injec ion. Unde he LHC Injec o Upg ade p og am, PS longi udinal ins abili ies ha e been
success ully o e come by ins alling a wide-band longi udinal eedback sys em (Fineme ca i y) and
educing he impedance o he 10 MHz RF sys em. Hence, he limi co esponding o he e ical ed
line in Fig.5 has been emo ed. A p esen , mo e han 3×1011 p o ons pe bunch can s ably be
ex ac ed om he PS in ains o 72 bunches. The equi emen on he longi udinal emi ance,
howe e , which should be small enough no o exceed he bunch leng h o 3.8 ns a he SPS injec ion
( o ensu ing ho izon al beam s abili y in he SPS), makes in ensi ies abo e 2.9×1011 p o ons pe
bunch ha dly usable.
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5.3 ADVANCED SCHEMES
The ad an ages o s ochas ic cooling a e pa icula ly signi ican o collide s. A RHIC, he 3D
s ochas ic cooling o U anium-on-U anium collisions has inc eased he in eg a ed luminosi y pe
s o e by a ac o o 5. O en, he s ochas ic cooling is used in combina ion wi h elec on cooling o
each he bes beam pe o mance.
The combina ion o elec on and s ochas ic cooling is p oposed o as cooling a he highes ene gies
h ough a no el scheme called he “Cohe en Elec on Cooling” sys em. The Cohe en Elec on
Cooling sys em has h ee majo subsys ems. 1) modula o : he ions o he beam imp in a “densi y
bump” on he elec on dis ibu ion; 2) ampli ie based on a high-gain ee elec on lase , on he
mic obunching ins abili y, o a plasma cascade; each o hese in e ac ions ampli ies a densi y bump
by o de s o magni ude; 3) kicke : he ampli ied & phase-shi ed elec on cha ge dis ibu ion is used
o co ec he eloci y o se o he ions. Such a “s ong had on cooling” scheme is conside ed o
possible deploymen a he Elec on Ion Collide (Fig. 11).
Fig. 11. The Elec on Ion Collide . In his p ojec , he b igh ness o he colliding beams is planned o be inc eased
h ough ad anced elec on cooling sys ems.
The ou main challenges o ealizing Cohe en Elec on Cooling a e: (1) high-cu en ERL, (2) a
low-noise elec on beam, (3) longi udinal alignmen o 1 mic on o e 100 m dis ance, and (4) he
con olled ampli ie [11].
A concep simila o Cohe en Elec on Cooling is also used o he Op ical S ochas ic Cooling. He e,
a Pickup Wiggle makes he beam emi synch o on adia ion, on which he cha ac e is ic ea u es o
he beam dis ibu ion a e imp in ed. The beam is anspo ed h ough he accele a o , and a he same
ime, he adia ion emi ed by he beam a he Pickup Wiggle is ampli ied h ough an op ical ampli ie
and hen injec ed in o a Kicke wiggle , whe e i in e ac s wi h he beam and applies he co ec ion
o cooling. This concep has been demons a ed wi h an elec on beam a he IOTA acili y in

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Fe milab in 2022 (Fig. 12), and i is conside ed an in e es ing op ion o cooling had on beams a he
highes ene gy.
Fig. 12. Scheme o he op ical s ochas ic demons a ion [12].
Among he no el concep s o ad anced cooling, Lase Cooling is now ecei ing a en ion as i is
p oposed as a main ool o expe imen al physics. In pa icula , a special lase cooling scheme o
pa icula s ipped ion beams is a key ing edien o he Gamma Fac o y p ojec [13]. Lase cooling is
also o eseen in he FAIR p ojec . Figu e 13 shows he Scho ky noise du ing he lase sweep. In his
pic u e, he ela i e equency wid h is d / =2x10-5
Fig. 13. Scho ky spec a a he ESR, du ing lase cooling o C3+. (le ) and he A gon ion lase (257.3 nm), equency
doubled, u ilized o his expe imen ( igh ).
The lase cooling is being p epa ed and se up o he SIS100 in a dedica ed lase cooling a ea, also
dedica ed o lase spec oscopy [14].
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6 The pa h owa ds he ul ima e b igh ness
The pa h owa ds ul ima e b igh ness equi es:
1) The c ea ion o a b igh beam a he linac sec ion. The injec ion o a synch o on should
minimize he dilu ion ac o , and a non-Liou illian injec ion me hod should be employed.
2) Con olling he e ec o space cha ge on beam deg ada ion. This is eached by esonance
compensa ion and p ope choice o he machine wo king poin . Addi ionally, space cha ge
compensa ion echniques could be de eloped, such as elec on lenses and “elec on columns”
o space cha ge compensa ion. Fo speci ic mechanisms deg ading he beam quali y, such as
he space cha ge-induced pe iodic c ossing o esonances, he longi udinal bunch shaping ia
mul i-ha monics RF sys ems may lead o signi ican bene i and g ea ly educe he esul ing
beam loss.
3) Collec i e e ec s mus be con olled ia p ope eedback sys ems and wi h p ope design o
componen s o s ay wi hin an accep able impedance budge .
4) The Beam Cooling emains a undamen al ool o each high-b igh ness beams. In pa icula ,
he u u e o beam cooling will be shaped by wo ypes o de elopmen :
1) Cooling a highe ene gies
• Lase cooling in SIS100 is one example
• The Elec on-Ion Collide (EIC) will signi ican ly bene i om beam cooling
op ions:
• elec on beam om a linac (ene gy eco e y linac)
• cohe en elec on cooling
• me ging o elec ons ci cula ing in a s o age ing
2) The high b igh ness beam will be ele an o wo eme ging Hea y Ion and Seconda y
Beam Facili ies: FAIR (Ge many) and HIAF (China). These p ojec s will need mo e
adi ional cooling sys ems, bu ope a ing o e a la ge ene gy ange and wi h a la ge
pa icle a ie y.
The highes b igh ness could be achie ed wi h 1D, 2D, o 3D c ys alline beams. 3D c ys alline beams
up o helix s uc u es su ounding a linea s ing we e c ea ed a he RF quad upole s o age ing
PALLAS in Ge many [15].
An ion-cloud con ined in a Paul ap acqui es Coulomb c ys alline s a e when cooled nea absolu e
ze o, he no malized emi ance o a Coulomb c ys al can be in he sub- em ome e ange. Ongoing
e o s a Hi oshima Uni e si y aim a demons a ing an ul ima e single-ion sou ce wi h ms emi ance
o o de 10−16 m om a wo-componen Coulomb c ys al. Expe imen s ha e al eady gene a ed a
Coulomb c ys al consis ing o calcium and ni ogen ions. The image o a wo-componen Coulomb
c ys al aken by an in ensi ied cha ge coupled de ice (ICCD) came a in Fig. 14. The b igh a ea o
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he ou e pa o he c ys al is he lase -induced luo escence om calcium ions. The da k a ea o he
inne pa is conside ed o include ni ogen ions, which do no emi ligh [16].
Fig. l4. Image o a wo-componen shell Coulomb c ys al a Hi oshima Uni e si y [16].
I he beam pa icles a e bosons, e.g., He nuclei (alpha pa icles), po en ially also a Bose-Eins ein
condensa e could be gene a ed h ough cooling; see Re . [17] and a icles ci ed he ein.
7 Conclusion
Beam b igh ness is comp omised and dilu ed by Liou ille’s heo em, by incohe en and cohe en
space cha ge e ec s, and by in abeam sca e ing. The ansi ion be ween space cha ge and sca e ing
is p esen ly no ully cap u ed in simula ions o heo ies.
The b igh ness o had on beams is ad anced wo ldwide by majo new p ojec s in Nuclea Physics,
including HIAF in China, FAIR in Ge many, and he EIC in he US. These lagship p ojec s. Along
wi h he Gamma ac o y p oposed a CERN, d i e o wa d mo e complex and mo e e icien injec ion
schemes, such as 2- o 3-plane injec ion, as well as ad anced beam cooling me hods. Eme ging and
e ol ing cooling echniques a e mo e lexible and/o mo e powe ul, wi h high-ene gy bunched-beam
elec on cooling, op ical s ochas ic cooling, lase cooling, and cohe en elec on cooling igu ing
among he on ie echniques.
C ys alline beams o Bose-Eins ein-condensa e beams could each an ul ima e le el o b igh ness.
B igh beams a e also undamen al o ealizing a nuclea clock as o eseen in he HITHOR p ojec
[18], whe e, by using highly cha ged 229Th ions—especially he one-elec on s a e 229Th⁸⁹⁺— he
nuclea hype ine mixing is exploi ed, which enhances nuclea exci a ion a es by up o a million old.
This app oach, enabled by he ad anced apping acili ies a GSI, will allow he i s lase exci a ion
o a nucleus, ushe ing in a new e a o p ecision imekeeping and undamen al physics explo a ion.
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8 Re e ences
[1] Jiancheng Yang, High in ensi y challenges in he HIAF p ojec , Space Cha ge 2024;
h ps://indico.ihep.ac.cn/e en /21466
[2] H. Ho chi, PRAB 23, 2020
[3] Guodong Shen, S udy on wo-plane pain ing injec ion scheme o HIAF B ing,
h ps://indico.ihep.ac.cn/e en /21466
[4] R.W. Hasse, I. Ho mann Space-cha ge limi s o mul i u n injec ion in HIDIF, NIM A, Volume
415, Issues 1–2, 21 Sep embe 1998, Pages 478-483
[5] O. Dolinskyy e al., Enhancing beam in ensi y in sis18 by a wo-plane mul i- u n injec ion
app oach, MOPS141, IPAC25
[6] Liangsheng Huang, Sou ce o ins abili y in he RCS o CSNS, Space Cha ge 2024;
h ps://indico.ihep.ac.cn/e en /21466
[7] Ma kus S eck, Beam Cooling, Space Cha ge 2024; h ps://indico.ihep.ac.cn/e en /21466
[8] HFHF Helmhol z Fo schunsakademie Hessen ü FAIR h ps://h h -hessen.de/en/
[9] A. Engeda, G. F anche i, In abeam Sca e ing in a 3D Poisson sol e , P oc. o IPAC2023, 7-12
May 2023, Venice, I aly; Alexande Engeda and Giuliano F anche i, Mac opa icle collisionali y in
PIC sol e , 2024 J. Phys.: Con . Se . 2687 062028
[10] J. Y. Du, X. N. Du, X. G. Liu, and Y. S. Yuan, 3D Space Cha ge Sol e Based on Tenso
Decomposi ion o High-In ensi y Beams, P og ess o Theo e ical and Expe imen al Physics, Vol.
2025, pp. 1-20, DOI: h ps://doi.o g/10.1093/p ep/p a 047
[11] S. Nagai se , p i a e communica ion (2025)
[12] Expe imen al demons a ion o op ical s ochas ic cooling, J. Ja is, V. Lebede , e al. Na u e
608 287-292 (2022)
[13] Wi ek K asny, The Gamma Fac o y P ojec , “Gigahe z Ra e and Rapid Muon Accele a ion”,
Be n 2023
[14] Danyal Win e s, Lase cooling aken o he ex eme: cold ela i is ic in ense beams o highly-
cha ged hea y, TUOGA2, IPAC23, TUOGA2.pd , 2023, Venice
[15] U. Sch amm, T. Schä z, and D. Habs, Th ee-dimensional c ys alline ion beams, Phys. Re . E
66, 036501 (2002)
[16] K. Mu oo, K. I o, H. Okamo o, An Ul ima e Single-Ion Sou ce Using a Coulomb C ys al in a
Paul T ap. IPAC24, MOPR71 (2024)
[17] L.M. Sa a o , I.N. Mishus in, and H. S oecke , Bose-Eins ein condensa ion in ini e d ops
o 𝛼 pa icles, Phys. Re . C 106, 014301 (2022)
[18] Highly Ionized T apped 229-Tho ium: A New Pa adigm Towa ds a Nuclea Clock
h ps://co dis.eu opa.eu/p ojec /id/101142155
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9 Annex: Glossa y
Ac onym
De ini ion
AD
An ip o on Decele a o a CERN
BNL
B ookha en Na ional Labo a o y on Long Island, U.S.A.
CERN
Eu opean O ganiza ion o Nuclea Resea ch in Gene a, Swi ze land
CSNS
Chinese Spalla ion Neu on Sou ce in Guangdong, P.R. China
CSR
C yogenic S o age Ring a MPI Heidelbe g
ESR
Expe imen al S o age Ring a GSI
FAIR
Facili y o An ip o on and Ion Resea ch a GSI
HIAF
High In ensi y Hea y-ion Accele a o Facili y a IMP
IBS
In abeam Sca e ing
IMP
Ins i u e o Mode n Physics – Chinese Academy o Science
IHEP
Ins i u e o High Ene gy Physics - Chinese Academy o Science
LINAC4
H- linac a CERN
PALLAS
Paul lase cooling accele a ion sys em a Munich’s Ludwig-Maximilians
Uni e si y
PS
P o on Synch o on a CERN
PSB
P o on Synch o on (PS) Boos e a CERN
RCS
Rapid Cycling Synch o on
RF
Radio equency
RHIC
Rela i is ic Hea y Ion Collide a BNL
SPS
Supe P o on Synch o on a CERN