NEUTRON PRODUCTION IN
NEUTRINO-NUCLEUS INTERACTIONS
WITH T2K
Asi S i as a a
a.s i as a [email protected]
XXI In e na ional Wo kshop on Neu ino Telescopes
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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• Long-baseline expe imen (295 km)
• Nea de ec o s (ND280, INGRID, WAGASCI-BabyMIND) a 280m om J-PARC
•�� peaks a 0.6 GeV a ND280 (2.5° o -axis)
Phys.Re .D 87,012001 (2013)
The T2K Expe imen
Rela ed Talks: S. King, L. Machado
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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• Supe -FGD is made o ~ 2 million scin illa o
cubes o size 1 cm which p o ide sub-ns iming
esolu ion.
ToF
TPCs
FGDs
Nea De ec o ND280 Upg ade
• HA-TPC does he iden i ica ion and econs uc ion
o pa icles a eling a high angles.
• TOF, along wi h SFGD, can di e en ia e be ween
incoming and ou going pa icles Rela ed Talks: G. Reina, M. Fel e, W. Okinaga-san
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Typical T2K
muon neu ino
ene gy ange
h ps://doi.o g/10.2172/1042577
Quasi-Elas ic
Sca e ing (CCQE) Del a Resonance
Neu ino-Nucleus In e ac ions
Rela ed Talk: E. Sand o d
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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• Pa icles p oduced a e neu ino-nucleus
in e ac ion can unde go FSI.
• This makes iden i ica ion o speci ic in e ac ions in
de ec o di icul .
• Iden i ying opology is a be e choice as i educes
model dependence.
Some opologies:
CC0π, CC1π, CC-mul i π, CC0πNn
Final S a e In e ac ions (FSI)
Pic u e
C edi s:
T.
Golan
p
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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CCQE (��� → �−�) : Wi h FSI
2p2h (���� → �−푛) : Wi h o wi hou FSI
(���� → �−) : Wi h FSI
Del a esonance : Wi h o wi hou FSI
Type o
in e ac ion
% in CC0πNn
(be o e FSI*)
% in CC0πNn
(a e FSI*)
CCQE
0% (0)
54.80% (1119)
2p2h
36.08% (245)
22.82% (466)
Del a es.
59.65% (405)
21.11% (431)
O he s
4.27% (29)
1.27% (26)
• La ge inc ease in e en s due o CCQE
and 2p2h unde going FSI
• CC0πNn opology can be used o es
FSI models
*FSI u ned ON o OFF he e is Nucleon FSI
In e ac ions in CC0πNn Topology
T2K WORK-IN-PROGRESS
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Neu on candida e in an ac ual e en
One neu on
candida e in
his e en
S
F
G
SFGD
HATPC
HATPC
TPC1 TPC2 TPC3
FGDs
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Ve ex
Muon T ack
Seconda y
Clus e
P ima y p o on
Selec ion o CC0π e en s
• One muon ack
• No pion ack
• Any numbe o p o on
acks
Seconda y
T ack
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Recons uc ing a neu on
• Neu ons deposi ene gy
away om he e ex.
• Le e a m and Time-o -
ligh a e ools o iden i y a
neu on and econs uc i s
ene gy.
Phys. Re . D 101, 092003 (2020)
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Ini ial pu i y o CC0πNn: ~ 30%
Wi h high BDT sco es, ~ 90%
pu i y is achie able.
T2K WORK-IN-PROGRESS
E en BDT Sco e
CC-1�+ in he plo is a ypo. I can be any o he h ee pions.
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Dis ibu ion o neu on candida es
( acks + clus e s) peaks a ound 2 - 4
neu on candida es.
T2K WORK-IN-PROGRESS
Numbe o neu on candida es
CC-1�+ in he plo is a ypo. I can be any o he h ee pions.
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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• ND280 upg ade has made econs uc ion o pa icles wi h sho e acks o smalle
ene gies e en be e .
• CC0πNn opology can be ins umen al in es ing FSI models.
• Neu ons lea e an ene gy deposi in he o m o a ack o a clus e away om he e ex.
• To iden i y neu on e en s, BDTs a e ained and hey gi e high signal pu i y.
• Cu en ly, wo k is in p og ess o de elop sys ema ics and s udy model dependence in
CC0πNn selec ion.
Summa y
Thanks o you a en ion!
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Neu on candida e in an ac ual e en
Two neu on
candida es in
his e en
SFGD
HATPC
HATPC
TPC1 TPC2 TPC3
FGDs
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Backup
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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• Neu inos p oduced in a speci ic la o s a e (��) wi h ene gy �
• A e a eling a dis ance �,
�� dec ease in numbe ⟹ �� disappea ance
�� inc ease in numbe ⟹ �� appea ance
• Sensi i i y o maximum oscilla ion depends on �/�
Neu ino Oscilla ions
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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• Neu inos p oduced in a speci ic la o s a e (��) wi h ene gy �
• Oscilla ion p obabili y depends on:
Neu ino Oscilla ions
Neu ino ene gy
T a elling dis ance (“baseline”)
PMNS mixing pa ame e s
Di e ence be ween mass s a es
Pa ame e s in PMNS ma ix
(�23, �13, �12, ���)
Known
Need o know
Wha is measu ed
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Neu ino Ene gy as Unce ain y
C. W e , NuSTEC2024
• Fo p ecise measu emen o oscilla ion
pa ame e s, neu ino ene gy mus be well-
econs uc ed.
• One o he leading sou ces o unce ain y in
neu ino ene gy econs uc ion a e neu ons
(calo ime ic) and in e ac ion models
(kinema ic).
• They ha e a high chance o escaping he
de ec o wi hou deposi ing any ene gy, hence,
c ea ing a p oblem in econs uc ing neu ino
ene gy.
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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NEUTRINO-NUCLEUS INTERACTIONS
Quasi-Elas ic
Sca e ing (CCQE)
Two-pa icle wo-hole
p ocess (2p2h)
Del a Resonance
��� → �−���� → �−푛
���� → �−
��� → �−∆+→ �−�+�
→ �−�0
��� → �−Δ++ → �−�+
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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CC0π p e-selec ed wi h seconda y acks
(minimum dis ance om all p ima y acks)
• Backg ound dis ibu ion peaks o acks close o
o he acks (~5 cm) and leads o impu e neu on
sample.
• These a e p ima ily due o muon hi s no used in
ack econs uc ion and del a elec ons p oduced
by p ima y muons.
T2K WORK-IN-PROGRESS
Co ec ion: All he muons, no jus TPC/HAT muon
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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Decision T ee
T ee dep h
Roo node
Spli ing
Lea
Image
Sou ce
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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P oblems wi h Single Decision T ees
Single decisions ee a e as and easy bu ha e p oblems:
1. Can lead o o e i ing, especially i deep, which means di icul
o gene alize o new e en s.
2. Migh no desc ibe he da a e y well i shallow.
3. Ins abili y: Small changes in da a can change he whole ee.
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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T ack and Clus e BDT Sco e
T2K WORK-IN-PROGRESS T2K WORK-IN-PROGRESS
T ack BDT sco e is o all he seconda y acks (a leas 3 cm om he econs uc ed p ima y e ex) in all CC0π-selec ed e en s. Same o
clus e s.
Signal means ha he seconda y objec is connec ed o a p ima y neu on h ough one o mo e sca e ings and ha neu on has he same
e ex as ha o he muon.
Neu on P oduc ion in Neu ino-Nucleus In e ac ions wi h T2K
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The e is a leas one neu on candida e in hese e en s. So, no clus e means ha he e is a leas
one ack and ice e sa.
T2K WORK-IN-PROGRESS
Numbe o neu on ( ack and clus e ) candida es
T2K WORK-IN-PROGRESS
CC-1�+ in he plo is a ypo. I can be any o he h ee pions.
