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Upg ade o ALICE o wa d de ec o s
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Published e sion
Slupecki, Maciej
Slupecki, M. (2019). Upg ade o ALICE o wa d de ec o s. In S. Choi, S. Y. Choi, J. E. Kim, Y. Kim,
U.-K. Yang, & Y. Kwon (Eds.), ICHEP2018 : P oceedings o The 39 h In e na ional Con e ence on
High Ene gy Physics (A icle 255). Sissa. POS P oceedings o Science, 340.
h ps://doi.o g/10.22323/1.340.0255
2019
PoS(ICHEP2018)255
Upg ade o ALICE o wa d de ec o s
Maciej Slupecki*†
Depa men o Physics, Uni e si y o Jy askyla,
P.O. Box 35, FI-40014 Uni e si y o Jy askyla, Finland
E-mail: [email p o ec ed]
ALICE will upg ade i s subsys ems in 2019−2020 o ully bene i om he inc eased collision
a e and luminosi y o he LHC a CERN. Two new o wa d de ec o s will be ins alled a he co e
o ALICE: he Fas In e ac ion T igge (FIT) and he Muon Fo wa d T acke (MFT). Addi ionally,
du ing he shu down be ween Run 3 and Run 4, he e will be an oppo uni y o ins all he Fo wa d
Calo ime e (FoCal). This pape desc ibes hese new o wa d de ec o s, hei physics jus i ica ion
and goals, selec ed design ea u es along wi h pe o mance o de ec o p o o ypes and simula ed
pe o mance igu es.
The 39 h In e na ional Con e ence on High Ene gy Physics (ICHEP2018)
4-11 July, 2018
Seoul, Ko ea
*Speake .
†on behal o he ALICE Collabo a ion
© Copy igh owned by he au ho (s) unde he e ms o he C ea i e Commons
A ibu ion-NonComme cial-NoDe i a i es 4.0 In e na ional License (CC BY-NC-ND 4.0). h p://pos.sissa.i /
PoS(ICHEP2018)255
Upg ade o ALICE o wa d de ec o s Maciej Slupecki
1. In oduc ion
The LHC is en e ing a wo-yea upg ade pe iod o Long Shu down 2 (LS2) in Decembe 2018.
A e ha he Pb−Pb ins an aneous luminosi y in Run 3 will inc ease by a ac o o 5−6. The up-
g aded ALICE expe imen [1] aims o eco d he minimum-bias Pb−Pb in e ac ions a he a ge
a e o 50 kHz, ha is 50 imes mo e han possible wi h he p esen se up. To cope wi h such
a d ama ic change in he unning condi ions and o achie e i s physics objec i es, ALICE will im-
plemen a as e eadou and eco d all o he minimum-bias e en s. Mo eo e , acking p ecision
a mid- and o wa d apidi y will be imp o ed, while p ese ing unique pa icle iden i ica ion ca-
pabili ies down o e y low pT. In addi ion o he new ITS acke and imp o emen s o he TPC,
wo new o wa d de ec o s will be ins alled du ing LS2: he Fas In e ac ion T igge (FIT) and he
Muon Fo wa d T acke (MFT). Figu e 1shows CAD d awings o hese de ec o s.
Figu e 1: Simpli ied enginee ing d awings o he MFT (middle) and he wo a ms o he FIT de ec o .
2. Fas In e ac ion T igge (FIT)
The FIT is composed o wo de ec o s cen e ed a ound he beam pipe on bo h sides o he
in e ac ion poin (IP). FIT-A, shown in Fig. 1(le ), is loca ed 3.3 m om he IP and co e s he
pseudo apidi y in e al o 2.2<η<5.0. I consis s o a la ge segmen ed plas ic scin illa o and
an a ay o Che enko modules. The Che enko a ay o FIT-C, shown in Fig. 1( igh ), is cu ed
o main ain cons an dis ance (0.82 m) om he modules o he IP. I co e s −3.4<η<−2.3. Fo
his o ical easons, he scin illa o ing is e e ed o as V0+ and he Che enko a ay, as T0+.
A single T0+ Che enko module consis s o ou op ically sepa a ed qua z adia o s (26.5×
26.5×20 mm3each) coupled o a modi ied Planacon XP85012 MCP-PMT [2]. The selec ed model
was ound o be he bes in e ms o p ice, pe o mance, compac size, and s abili y o ope a ion.
The c oss- alk be ween he channels has been educed by modi ica ions o he PCB backplane. The
segmen ed anode o a modi ied Planacon is g ouped in o quad an s ma ching he co e age o he
indi idual adia o s and con e ing each module in o ou independen de ec o channels (pixels).
The in insic ime esolu ion o each pixel is be e han 13 ps. The ull-chain single-MIP esolu ion
is below 50 ps. Each de ec o channel co e s he dynamic ange o 1 o 500 MIPs.
The V0+ is a 1.48 m diame e scin illa o disk, di ided symme ically in o 45° oc an s. The
oc an s a e subdi ided in o 5 ings o inc easing adii so ha each ing has a simila pseudo apidi y
co e age o ∼0.6. In o al he e a e 40 op ically isola ed sec o s. The ac i e pa o he V0+ is
made o a 4 cm hick EJ-204 plas ic scin illa o . The back su ace o he scin illa o is op ically
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PoS(ICHEP2018)255
Upg ade o ALICE o wa d de ec o s Maciej Slupecki
coupled o a g id o clea op ical ibe s, a ached pe pendicula ly o he scin illa o , and spaced by
3−7 mm. The ibe s om each cell a e bundled oge he and connec ed o a Hamama su ine-mesh
PMT (R5924). The measu ed ime esolu ion o he V0+ is 120 ps o he in e nal ings and 300 ps
o he ex e nal ing. The lowe esolu ion o he ex e nal ing is due o i s la ge a ea and spa se
ibe g id densi y. The V0+ makes a c ucial con ibu ion o he FIT unc ionali y, especially in
e ms o cen ali y and e en plane esolu ion (see Fig. 2).
Figu e 2: Le : Cen ali y esolu ion o di e en componen s o FIT as a unc ion o cen ali y simula ed
o Run 3 ene gy. Righ : E en plane esolu ion as a unc ion o cen ali y, simula ed in Run 2 condi ions.
The FIT will unc ion as he main ALICE luminome e wi h a di ec eedback o he LHC. I
will p o ide a clean minimum-bias igge by ejec ing beam-gas in e ac ions and ul a pe iphe al
collisions. The o e all igge e iciency o pp collisions will be imp o ed wi h espec o he
p esen ALICE appa a us. The FIT will be capable o online e ex posi ion de e mina ion wi h
a esolu ion along he beam di ec ion be e han 17 mm. I will also gene a e cen ali y-based
igge s. The FIT da a will be used o de e mine unbiased o wa d mul iplici y needed o ex ac
he cen ali y and he eac ion plane o each e en . The FIT will also p o ide a p ecise collision
ime o he Time-o -Fligh -based pa icle iden i ica ion.
3. Muon Fo wa d T acke (MFT)
A simpli ied d awing o he MFT [3] is shown in Fig. 1(middle). The MFT co e s he pseu-
do apidi y o −3.6<η<−2.5. I consis s o 5 disks loca ed be ween he in e ac ion poin and
he had on abso be o he Muon Spec ome e . The disks a e ins umen ed on bo h sides wi h
ALICE pixel de ec o s (ALPIDE). The ALIPIDE chips a e used o he upg ade o bo h he ITS
and he MFT. The single pixel size is 27 ×29 µm2. The small hickness o 50 µm helps o educe
he ma e ial budge down o 0.7% o a adia ion leng h pe disk. The de ec o is also adia ion-ha d
and will be able o wi hs and up o 400 k ad, which is abou 10 imes he expec ed dose collec ed
du ing he LHC Run 3 and Run 4 ope a ion. The MFT eadou will be capable o eco ding Pb−Pb
collisions a he a ge in e ac ion a e o 50 kHz and pp collisions – up o 1 MHz.
The physics mo i a ion o he MFT de ec o [3] is he measu emen o beau y p oduc ion a
o wa d apidi y using J/ψmesons o single muons om b-had on decays, as well as he imp o e-
men o he measu emen s o p omp J/ψand ψ(2S) s a es. Figu e 3shows he compa ison be ween
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PoS(ICHEP2018)255
Upg ade o ALICE o wa d de ec o s Maciej Slupecki
Figu e 3: Compa ison o he signal- o-backg ound a io o J/ψand ψ(2S) wi hou (le ) and wi h he MFT
( igh ). The plo s show esul o simula ions o 10% mos cen al Pb−Pb collisions a √sNN =5.5 TeV
no malised o he expec ed in eg a ed luminosi y o 10 nb-1 [4].
simula ed pe o mances o p esen -day Muon Spec ome e only (le ) and a e he ins alla ion o
he MFT ( igh ). The imp o emen o signal- o-backg ound a io eaches one o de o magni ude,
which la gely inc eases he s a is ical signi icance o he ψ(2S) signal.
4. Fo wa d Calo ime e (FoCal)
The FoCal is a Fo wa d Calo ime e [5] p oposed o ins alla ion du ing LS3. I s ou s anding
ea u e would be he inclusion o wo high-g anula i y laye s, made o Monoli hic Ac i e Pixel Sen-
so s (MAPS), which imp o e acking esolu ion and allow o disc imina ion be ween di ec and
decay pho ons, and p o ide a wo-showe sepa a ion. The FoCal would ex end he physics scope
o he ALICE de ec o by p o iding measu emen s o di ec pho ons down o Bjo ken-x10−6in
p-Pb collisions. This will yield impo an in o ma ion on high-densi y gluon dynamics in Pb nuclei
a unp eceden ed low x. I will also cons ain nuclea pa on dis ibu ion unc ions (PDF) and may
shed new ligh on possible non-linea PDF e olu ion e ec s and he onse o gluon sa u a ion.
5. Conclusions
The MFT and FIT de ec o s will be ins alled in ALICE in ea ly 2020. The de ec o s each o
exceed he design pa ame e s equi ed by he physics objec i es. The FoCal has been p oposed o
be added o ALICE du ing he Long Shu down 3 (2024−25). I implemen ed i p omises new and
exci ing esul s ela ed o nPDFs and gluon dynamics a e y low Bjo ken-x.
Re e ences
[1] B. Abele e al. Upg ade o he ALICE Expe imen : Le e O In en . J. Phys., G41:087001, 2014.
[2] W. H. T zaska. New Fas In e ac ion T igge o ALICE. Nucl. Ins um. Me h., A845:463–466, 2017.
[3] J. Adam e al. Technical Repo CERN-LHCC-2015-001. ALICE-TDR-018, CERN, Jan 2015.
[4] Technical Repo CERN-LHCC-2013-014. LHCC-I-022-ADD-1, CERN, Gene a, Aug 2013.
[5] N. an de Kolk. JINST, 13(03):C03030, 2018.
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