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Jlab Hall C transition from 4 GeV to 11 GeV
H. Mkrtchyan
Yerevan Physics Institute,
ANSL (YerPhI)
2
Outline CEBAF accelerator from 4 GeV energy to 6 GeV, and 12 GeV upgrade Hall C at 4-6 GeV CEBAF YerPhI group contribution in Hall C at 6 GeV era Hall C transition from 6 GeV to 12 GeV 12 GeV energy experiments in Hall C and proposed schedule YerPhI group contribution in Hall C 12 GeV upgrade Hall C current status and YerPhI group activities
3
Important historical dates for CEBAF:
In early 1979 a group of physicists assembled at the University of Virginia for a
conference “Future Possibilities for Electron Accelerators”, to discuss new
approaches to design electron accelerator with ~100% duty factor
This dream had its origins in the 1950s, when Hofstadter and McCarthy
discovered at Stanford’s High Energy Physics Laboratory (used high frequency
electron accelerator Mark III) about the internal structure of nuclei and nucleons.
Its comes clear that future investigations in these areas required higher energies
and better duty factor. This line led to the construction in 1960s of SLAC and
1970s Bates-MIT 400 MeV linac.
In December 1979 NSAC approved proposal for construction of 2 GeV energy
machine by 1985. The beam on target required to be continuous, not pulsed.
The National Bureau of Standards, the University of Illinois, Argonne National
Lab, and MIT-Bates – were established as centers to develop the machine project.
History of how CEBAF was founded
4
In April 1982 NSAC gave highest scientific priority to a high duty factor electron
accelerator of energy 4 GeV, to explore the quark structure of the nucleus.
In April 1983 from the five design first was selected only two, then final one.
(All magnets assumed to be regular “room-temperature” technology. One linac
and several arcs for the beam recirculation.)
To obtain the continuous beam, this conventional accelerator was to work in
combination with a pulse stretcher ring.
History of how CEBAF project was selected
In1985 Grunder led CEBAF as a first director. He proposed build complex with two
linacs and arcs, based on superconducting radiofrequency accelerating technology
5
4 GeV energy CEBAF
By December1993 CEBAF accelerator was ready for commissioning
In summer 1994 first 4 GeV energy electron beam was delivered in Hall C
Experimental program started in 1995
Continuous Electron Beam
1497 MHz operation
Every third pulse to each hall
Simultaneous delivery 3 halls
499 MHz per hall, ~2 ps beam
pulses every 2 ns
Injector Energy 45 MeV
Linac Energy 400 MeV (each)
Beam Energy 0.8-4.0 GeV
Maximum current 200 μA
Beam polarization ~75%
Luminosity up to 1038 cm2/s
Energy spread dE/E ~10-4
Accelerator CEBAF consist of an injector, two superconducting
linac, two sets of arcs and systems of an electron beam extraction
from the accelerator and beam separation between halls.
The injector provide quasi-continuous electron beam with
bunches frequency 499 MHz per each hall and accelerator
frequency is 1.497 MHz.
6
Hall C at CEBAF 4-6 GeV
HMS SOS
Nearly identical detector packages
HMS
SOS
7
Number Experiment Grade Approved Days
E-89-008 Inclusive Scattering for Nuclei at x>1 and High Q2 B 8
E-89-009 Investigation of the Spin Dependence of the ΛN Interaction B+ 25
E-89-012 Two-Body Photodisintegration of the Deuteron at Forward Angle A- 10
E-91-003 Charged Pion Electroproduction in D2, 3He and 4He B+ 21
E-91-013 Energy Dependence of Nucleon Propagation in Nuclei B- 24
E-91-016 Electroproduction of Kaons and Light Hypernuclei A- 21
E-93-018 L/T Cross Section Separation in p(e,e’K±)Λ(Σ) for 0.5
8
Number Experiment Grade Approved Days
E-01-004 Charged Pion Form Factor (Extension E93-021) A- 14
E-01-006 Precision Measurements of the nucleon spin structure functions B+ 14
E-01-011 Spectroscopic Study of Lambda Hypernuclei A- 19
E-01-107 Measurement of Pion Transparency in Nuclei A- 14
E-02-017 Status of the ΛS=1 Hadronic Weak Interaction Program B+ 7
E-02-019 Inclusive Scattering from Nuclei at x>1 and high Q2 A 28
E-03-008 Sub-threshold J/Psi Photoproduction B+ 7
E-03-103 Measurement of the Nuclear Dependence of Structure Functions A- 10
E-04-001 Measurement of F2 and R on Nuclear Target in Resonance Region B+ 5
E-04-019 Two Photon Exchange Contribution in ep Elastic Scattering A- 18
E-04-101 Parity Violating Asymmetry in the N to Delta Transition B
E-04-108 Measurement of GEp /GMp to Q2=9 GeV2 via recoil polarization A 40
E-04-115 G0 Backward Angle Measurement A 70
E-05-115 Spectroscopic investigation of the Hypernuclei in the wide mass region A- 20
E-06-008 G0 Experiment: Backward Angle Measurement at Q2=0.23 GeV2 A 34
E-06-009 R=σL∕σT on Deuterium in the Nucleon Resonance Region A- 9
E-07-002 Polarization transfer in Wide Angle Compton Scattering B 3
E-07 003 Spin Asymmetries on the Nucleon Experiment-SANE A 34
E-08-016 The Qweak Experiment: Measurement of the Proton weak charge A 198
Hall C Experiments at CEBAF 4-6 GeV energies
* Experiments in which YerPhI group contribution was essential
9
Hall C results at 6 GeV: Fπ (E93-021 & E01-004)
The Fπ(Q2) extraction requires a model of the 1H(e,e’π+)n and thus is model dependent
The charged pion form factor Fπ(Q2) has been measured for Q2=0.60-2.45 GeV2
dtd
d
dEdd
d
v
Kee
25
2coscos)1(22
2
dt
d
dt
d
dt
d
dt
d
dtd
dTTLTLT
To separate contributions the cross section at low and high
ε as a function of ϕ for fixed values of W, Q2 and t needed
At small –t the σL is dominated by t-channel process and
Form factors play an important role in our understanding the structure of hadrons
The pion is the simplest hadronic system (bound state of quark and anti-quark)
The charged pion form factor Fπ(Q2) is an important quantity that can be used to
advance our knowledge of hadronic structure.
e+p→e’+π++n
),()()(
~222
22
2
tQFtgmt
tQ
NNL
10
Hall C results at 6 GeV: GEn, GMn (E93-038)
e
e’
n
n n ( e, e’ n )
E93-038 measured the ratio GEn/GMn via the recoil neutron’s polarization in the quasielastic
reaction at Q2=0.45, 1.13 & 1.45 GeV2. HneeH 12 ),(
• In polarized electron unpolarized neutron elastic
scattering, one can access to neutron form factors
by measuring transverse (Pt) and longitudinal (Pl)
components of recoil nucleon polarization :
HneeH12
),(
ME
M
e
E
e
ME
etGG
GG
GG
PP
222
2tan)1(2
2tan)1(2
2
222
222
2tan)1(2
2tan
2tan)1()1(2
M
M
e
E
e
M
elG
GG
G
PP
MEltGGPP
• Because of the lack of a free neutron target, the neutron form factors are known with less
precision than are the proton form factors, and measurements have been limited to small Q2.
• Before polarization experiments GEn were extracted from the quasielastic cross
section data and the deuteron elastic structure function A(Q2 ) with very large uncertainties.
• Secondary scattering (polarimeter) needed to define
Pl and Pt components of recoil neutron polarization
In 2000s these were most precise data at Q2>1 GeV2.
11
Hall C results at 6 GeV: Gen (E93-026)
• In this experiment the electric form factor of the neutron was determined from
measurements of the reaction for quasielastic kinematics.
• Polarized electrons were scattered off a polarized ammonia (15ND3) target in which the
deuterium polarization was perpendicular to the momentum transfer.
•To determine Gen the helicity dependent rate asymmetry in electron-neutron scattering was
measured. The scattered electrons were detected in HMS, and the neutrons in neutron detector.
• If the neutron polarization vector in the scattering plane and perpendicular to the momentum
transfer , then Gen is related to the beam-target asymmetry term by
),( npeed
• The value of Gen was determined by
comparing the acceptance averaged
value of the data to that of MC.
q V
enA
24
2MQ222
2tan)1(2
2tan)1(2
M
e
E
e
MEV
en
GG
GG
A
V
enA
E93-026 value:
GEn = 0.0526 ± 0.0033(stat) ± 0.0026(sys) for Q2=0.5 GeV2
GEn = 0.0454 ± 0.0054(stat) ± 0.0033(sys) for Q2=1.0 GeV2
12
Hall C results at 6 GeV: Gep-III (E04-108) • Jlab’s precise recoil polarization experiments established that
the proton electric form factor GEp falls faster that the magnetic
form factor GMp for momentum transfers Q2>1 GeV2.
• This in disagreement with results obtained from unpolarized
cross section measurements data (Rosenbluth separation)
• The polarization of the recoil proton in the elastic scattering
of longitudinally polarized electrons from unpolarized
protons has longitudinal (Pl) and transverse (Pt) components
with respect of the momentum transfer in the scattering plane.
• The ratio Pl/Pt is proportional to GEp/GMp:
2tan
2
e
p
ee
l
t
pp
M
p
E
p
M
EE
P
P
G
GR
• .In GEp-III, polarized electrons were scattered from 20 cm
liquid hydrogen target and detected in ~2000 channel BigCal.
HMS spectrometer with double FPP polarimeter was used to
detect recoil protons and measure polarization components.
13
View from downstream
Hall C results at 6 GeV: G0 (E00-006 & E04-115)
• The G0 have measured parity-violating asymmetry in elastic
electron-proton and quasi-elastic electron-deuteron scattering
over the range of 0.12 < Q2
14
Hall C results at 6 GeV: Qweak (E08-016)
M
MA
PV
weak
LR
LR
PV
2
The parity-violating weak amplitude can be accessed through the asymmetry APV:
)(22
0QBQQAA
p
WPV
24
2
0
QGA
F
012.0064.0 p
WQ
007.00710.0 p
WQ
Precision test of the Standard Model
(at Q2 ≈0.025 GeV2 small effect)
weakMMM
2~
2
Qweak proposes a 3% measurement of at Q2 ≈0.025 GeV2
• Required ~150 μA beam current, ~80% polarization, 2.5 kWatt power 35 cm long
cryotarget, careful control of backgrounds, Q2, polarization and false asymmetries
• Qweak experiment Aep = -279±35 (stat)±31(syst) ppb (4% of data)
• Standard Model Aep~ -216 ppb (parts per billion)
B(Q2) is hadronic structure (small at Q2 ≈0.025 GeV2)
• Global fit using all data
• Standard Model value
p
WQ
Elastic e + p scattering
15
E00-108: Quark-hadron Duality in Meson Electroproduction
• We have measured semi-inclusive electroproduction of π± from
proton and deuteron target, using 5.479 GeV energy beam.
• We have observed, for the first time, the quark-hadron duality
and low energy factorization in pion electroproduction reactions.
• Several ratios constructed from the data exhibit the features of
factorization in a sequential electron-quark scattering and a
quark-pion fragmentation
XeNe
The Pt dependence of cross section show a
possible flavor dependence of the transverse
momentum dependence of PDFs and FFs.
Extracted ratios on average agree with the QPM
expectations and with the existing high W2 data.
YerPhI group contribution in Hall C at 4-6 GeV
2πq
i
2
iQz,DQx,qσ
16
YerPhI group contribution in Hall C at 4-6 GeV
• Design and construction electromagnetic calorimeters for HMS & SOS magnetic spectrometers. Development their software and calibration code.
• Design and construction threshold Aerogel detector for the HMS.
• PMTs gain monitoring system for the calorimeters and Neutron detector
• Refurbishing HMS hodoscopes, Neutron detector, Lucite Cherenkov
• Participation in installation and data taking in all Hall C experiments
• Leading role in the of-line analysis of Fpi, Mduality, Gen experiments
• Responsibility for the PID system of the HMS and SOS spectrometers
• Leading role in “Meson Duality” proposal and experiment
Two nearly identical calorimeters for HMS & SOS Two type aerogel detectors for HMS
Not full list of YerPhI group contribution in Hall C:
17
CEBAF from 4 GeV energy to 6 and 12 GeV
The 4 GeV CEBAF each linacs has 400 MeV energy provided by 20 cryomodules
(20 MeV / module). Each cryomodule consisted of eight 5-cell and 0.5 m length
cavities with accelerating gradient of ~5 MeV/m (2.5 MeV /cavity).
This goal was surpassed in 2006-2007. The accelerator cavities operate at an
average of ~7.5 MeV/m, and substantially higher energy (6 GeV) were expected.
The achievement of med-2009 to operate CEBAF at 6 GeV (50% higher than the
projected 4 GeV) was crucial for 12 GeV upgrade program.
The12 GeV project includes removing and refurbishing cryomodules to increase
cavity gradient from 5 MeV/m to 12.5 MeV/m (increase energy: 20 50 MeV).
There are 5 empty “zones” at the end of each linac. Installing five cryomodules
with-100 MeV capability in these locations would lead to linacs of 1.1 GeV each,
and 11 GeV beam with 5 passes.
C50 cryomodules each for 50 MeV (refurbished from original 5-cell cavities)
C100 have eight 7-cell cavities and on average provide 100 MeV (length of each
cavity is ~0.7 m with accelerating gradient 17.5 MeV/m, or 12.25 MeV/cavity)
18
CEBAF from 6 GeV 12 GeV
A cryomodule for the 12 GeV upgrade
installed in the CEBAF accelerator tunnel
Reassembly of a reprocessed C50 cavity pair into a one-
quarter-cryomodule (before assembly into helium vessel)
Original CEBAF 5-cele cavity
CEBAF 7-cell upgrade cavity.
19
Accelerator CEBAF upgrade project included:
Upgrade of the Cryomodules to increase the
injector energy from 45 MeV to 123 MeV
New accelerating cryogenic modules C-100
(developed at JLab)
Add 10 new C100 modules (five per each linac)
Add new arc in “West” arcs set to increase
number of pass
New extraction line for hall D
CEBAF Accelerator from 6 GeV to 12 GeV
Timing of the 12 GeV upgrade project:
May 2011 – November 2011: two new cryomodules
C100 were installed for test (one per linac)
June 2012 – October 2013: complete upgrade of
accelerator CEBAF
November 2013 – January 2014: running CEBAF
accelerator with energy 2.2 GeV (one pass)
January-May 2014: run the accelerator with the
beam energy 6.6 GeV (testing the systems & beam
for Hall A)
September 2014 – May 2015: the energy of the
beam up to 9 GeV. Beam delivery to Hall D.
September 2015 – May 2016: 12 GeV beam energy.
The beam delivery to halls B and C.
March 2017: the end of 12 GeV upgrade project.
20
The 12 GeV Groundbreaking ceremony: 14 April 2009
CEBAF from 6 GeV 12 GeV
Jlab director Hugh Montgomery, accelerator
division associated director Andrew Hutton, Jlab
former director Christophe Leeman and director of
operations Arne Freyberger shutting down CEBAF
On 18 May 1212 Jlab shut down its 6 GeV
CEBAF accelerator for 12 GeV upgrade
Jlab director Hugh Montgomery (center), former
directors Herman Grander (right) and Christophe
Leeman (left) at “CEBAF 12 GeV upgrade and
Hall D construction” Groundbreaking ceremony.
21
CEBAF Experimental Halls at 12 GeV
Due to limited funds in Hall A will be upgrade only beam line, Moller and
Compton polarimeters, keeping existing two 4 GeV/c HRS spectrometers
unchanged. In the future, for specialized experiments new SPS (Super Big-
Bite Spectrometer) and equipment for Moller experiment will be created in
Hall A.
Hall B will be equipped with a large acceptance spectrometer CLAS12
consisting of two superconducting magnets: a six-sector torus with
maximum field 2.3 T and a ~1 m long solenoid with a maximum field 5 T..
Some of existing detectors will be used, Will be added silicon-strip vertex
tracker, RICH and preshower. CLAS12 will have 10 times higher luminosity
than the CLAS.
In the Hall C a new spectrometer will be installed (which replaced SOS).
The pair of HMS and SHMS spectrometers allows for high-precision cross
section measurements and L/T separations in valence quark region.
A new Hall D is designed to conduct experiments on the photon beam and
for the study of new exotic states. Equipment includes a diamond target (for
polarized photon beam production and Gluex detector,
22
Hall C at CEBAF 12 GeV
23
Number Experiment Grade Approved Days Non-standard Equipment
E12 -06-101 P ion Form Factor A 30
E12-06-104 SIDIS R A- 30
E12-06-105 Inclusive at x>1 A- 30
E12-06-107 Color Transparency at 12 GeV B+ 30
E12-06-110 Spin asymmetry A1n, pol. 3He A 30 Polarized He3 target
E12-06-121 Neutron g2 and d2 at high Q2 A- 30 Polarized He3 target
E12-10-002 F2 at large x in res. region B+ 35
E12-10-003 d(e,e’p) at very high momentum B+ 35
E12-10-008 Nucl. dependence of F2, EMC A- 35
E12-11-002 Proton recoil pol. in 4He, 2H, 1H B+ 37
E12-11-009 Neutron FF at Q2 up to 7 GeV2 B+ 37 Magnet + Neutron polarimeter
E12-07-105 Exclusive (e,e’π), L-T separation A- 38
E12-09-002 pi+/pi- and Charge Sym. Viol. A- 38
E12-09-011 L-T in (e,e’K) Excl. at 5-11 GeV B+ 38
E12-09-017 Trans. Moment. in SIDIS pi0 A- 38
E12 -11-007 SRC and EMC (e,e’ backward p) B+ 38 Hall B TOF bars
E12-13-007 SIDIS Pi0 A- 40 Neutral Particle Spectrometer
E12-13-010 DVCS + Exclusive Pi0 A 40 Neutral Particle Spectrometer
E12-14-002 Nuclear Dependence of R B 42 Neutral Particle Spectrometer
E12-14-003 WACS at 8 and 10 GeV A- 42 Neutral Particle Spectrometer
E12-14-005 Wide angle Exclusive pi0 B 42 Neutral Particle Spectrometer
E12-14-006 Helicity correlation in WACS B 42 Neutral Particle Spectrometer
Approved and Conditional 12 GeV Hall C Experiments
Total Days ~800
24 24
Hall C Physics at 12 GeV Energy
25 25
Hall C Timeline
26 26
Early running plans – Year 2016
• Precommissioning detector checkout
~25 PAC days for Commissioning of Hall C
• Proposed Experiments for Commissioning:
• E12-06-107 Search for color transparency at 12 GeV
- only first part, A(e,e’p), relatively “easy” coincidence measurement
• E12-10-002 Precision measurements structure functions at large x
- momentum scan in this experiment will help understand acceptance
• E12-10-108 Nuclear dependence of F2 (EMC Effect)
- Light nuclei part can be combined with F2 run
- point target needed for this experiment will help acceptance studies
- low cross section part of experiment will check capability of equipments
dpF
,
2
27
E12-06-107: The Color Transparency at 12 GeV
• Goal of proposal to measure the A(e,e’p) and the A(e,e’π) cross sections to
extract the proton and pion nuclear transparencies in the nuclear medium
• Nuclear transparency defined as the ratio of the cross section per nucleon
on a bound nucleon in the nucleus to the cross section on a free nucleon.
• The basic idea is that, at high Q2 three quarks of the proton (two of pion)
could form a “color neutral” object of reduced transverse size, and pass the
nuclear medium undisturbed
A(e,e’p) cross-section on 1H and 12C
with 80 μA, of 8.8 & 11.0 GeV beam.
(Q2 = 8,10, 12, 14 & 16.4 GeV2)
• E12-06-017 will perform the proton
transparency measurements on 12C over
the range of Q2 = 8-16 (GeV/c)2
•The π+ transparency measurements will
be performed on 1H, 2H, 12C, and 63Cu,
over the range Q2=5-9.5 (GeV/c) 2
• A signature for the Color Transparency
(CT) would involve a dramatic rise in
the nuclear transparency with rise of Q2
28
• The differential cross section of electron-nucleon scattering can be written as:
, . σM is the Mott cross section for point-like nucleon, )2(2
tan)2
,(1
2)2
,(2
2
QWQWM
Edd
d
)(22
1)(
11MW and )(
2)(
22xF
xxFx
ii
xqi
exFW
E12-10-002: Precision Measurements of the F2
• New Data from Jlab show that Bloom-Gilman
duality holds well down to Q2~1 GeV2. However, a
growing with Q2 discrepancy was observed for at
large x. This in contradiction with the expectation
that duality should work best with increasing Q2.
and W1 and W2 are the nucleon structure functions.
• When the energy is high enough the structure functions can be expressed as a
functions of the only Bjorken x:
• In 70s Bloom & Gilman observed that the inclusive structure functions at low
energy follows a global scaling curve which describes high-energy data.
The ratio of integrals of F2 resonance data
and the QCD fits remains constant in Q2
Goal of proposal: extend proton and deuteron F2
structure function data to x~0.99 and Q2 ~17 GeV2
by measuring H(e,e’) and D(e,e’) cross sections in
the resonance region and beyond.
pF
2
29
E12-10-008: Nuclear dependence of F2 (EMC effect)
• In 80s the EMC found significant deviation between the
structure functions of heavy (Fe) and light (D) nuclei.
• Since then, the x and nuclear dependence (A-dependence)
of structure functions has been extensively studied, but the
origin of the EMC effect still is not understood.
Goal of proposal to perform inclusive
electron scattering measurements from
several light to medium nuclei over
range of 0.1 < x < 1 up to Q2 ≈15 GeV2.
• Experiments have looked for evidence of modification
the nucleon structure functions (form factors) in medium.
•Assuming that the shape of the EMC effect is universal,
and only the magnitude varies with target nucleus, one
can compare light nuclei by taking the x-dependence of
the ratio in the linear region, 0.35
30
Early running plan: Years 2017-2018
31
E12-09-017: Transverse Momentum Dependence of Semi-
Inclusive Pion and Kaon Production
• Not much is known about the orbital motion of partons • Significant net orbital angular momentum of valence quarks
implies significant transverse momentum of quarks
Goal: Map the pT dependence of π+ and π-
production off proton and deuteron targets to
study the kT dependence of u and d quarks
Final transverse momentum of the detected
pion Pt arises from convolution of the struck
quark transverse momentum kt with the
transverse momentum generated during the
fragmentation pt. Pt = pt + z kt +O(kt2/Q2)
Pt dependence very similar for both targets.
Deuterium slopes systematically smaller?
Assuming the width of the quarks (μu, μd) and
width of the fragmentation functions (μ+ μ-)
are Gaussian, and that the convolution of these
distributions combines quadratically, the total
width for each combination can be given by:
D+(z)
1)
2μ
2d
μ2
(zd
b and 1
)2
μ2u
μ2
(zu
b
Spokespersons R. Ent, P. Bosted, H. Mkrtchyan
32
E12-06-104: Measurement of the R = σL/σT in SIDIS
Goal: perform measurements on LH2 and LD2:
i) R as a function of z at x=0.20 & Q2 =2.0GeV2;
ii) map RH versus z at x = 0.40 and Q2 = 4.0 GeV2;
iii) map RH versus of PT at x=0.3 and Q2=3.0GeV2
Pt dependence very similar for both targets.
Deuterium slopes systematically smaller?
▪ In the asymptotic limit, in the quark-parton model the electro-produced pions are the fragmentation products of the spin-1/2 partons, and the ratio R = σL/σT disappears like 1/Q
2, like in the inclusive DIS. ▪The handbag diagram model (developed for the pion electroproduction), factorize these processes into a hard-scattering process and a soft process, and anticipate a behavior R = σL/σT ~ Q
2 at constant x, in the asymptotic limit. ▪At low energies and at large PT RSIDIS must anneal to RDIS for consistency.
Spokespersons R. Ent, P. Bosted, H. Mkrtchyan
33
E12-13-007: Measurement of Semi-Inclusive 0 Production as Validation of Factorization
Spokespersons: R. Ent, T. Horn, H. Mkrtchyan & V. Tadevosyan
• Essential ingredient of basic (e,e’) cross section measurements to lay a solid foundation for the SIDIS program at a 12-GeV JLab.
JLab Theory Group Report (Prokudin & Radyushkin):
• No diffractive r contributions • Smaller radiative tail - no pole contributions • Less resonance region contributions - for example, compare with ep e-D++ • Proportional to average fragmentation function - easier to disentangle quark and fragmentation functions
Why need for (e,e’0) beyond (e,e’+/-)?
34 Slide from Hugh Montgomery.
Hall A meeting, December 2014
35
SHMS Structure Assembly Underway
April 2014
August 2013
March 2014
February 2014 January 2014
October 2013
36
SHMS Structure Assembly Underway
April 2014
Detector hut
January 2015
Detector hut
1st Quadrupole 2nd Quadrupole
Q1 and Q3
View from Q1 to Q3
37
SHMS Detectors Status
Drift Chambers: HU
Scintillation Hodoscopes: JMU
Noble Gas Cherenkov: UVA Heavy Gas Cherenkov: UR
Quartz Hodoscopes: NCAC&T
Calorimeter: YerPhI Aerogel Cherenkov: CUA & YerPhI
S1X: 13 paddles @ 8 x 100 x 0.5 cm3
S1Y: 13 paddles @ 8 x 100 x 0.5 cm3
S2X: 14 paddles @ 10 x110 x 0.5 cm3
Two identical modules of six planes
each, 5mm drift distance, Ar+CO2 gas
2.3 m long Ar/Ne radiator
at atmospheric pressure
Diameter 1.6 m, length 0.6 m, C4F8O
gas, variable pressure, with n-1< 0.001
Assembly most of the detectors completed,
cosmic studies well underway. Installation
in the SHMS hut: end 2014 & spring 2015.
Aerogel with n=1.03, 1.02, 1.015 and
1.01. Effective area ~100 x 110 cm2
Preshower: 28 TF-1 type Pb0Glass
blocks, Shower: 224 F-101 type Pb-
Glass blocks. Effective area ~1.2 m2
S2Y: 21 Quartz bars, each about 1 m
long, width 5.5 cm , thickness ~2.5 cm.
38
CEBAF Accelerator status
• 12 GeV energy Beam line elements to the halls installations are completed.
• All radiofrequency and cryogenic module installation has been completed.
• All supplies for arcs magnetic elements are installed onsite and various stages of
checkout have been completed.
• 2.2 GeV/pass tune beam was transported to Hall A, B and D. This energy is a new
record for one pass and is the machine performance needed to eventually deliver 12
GeV beam to Hall D and 11 GeV beam to Halls A, B and C.
• This demonstrates the Performance Parameters needed for the 12 GeV CEBAF
Upgrade project.
• On December 2014 the accelerator was able to deliver 7 GeV energy CW beam to
the Hall A for DVCS experiment. Work is progressing to provide continuous wave
beam to Hall A/B/C/D for commissioning.
• Work in the Hall D Tagger area continues.
39
YerPhI contribution in 12 GeV upgrade: Calorimeter SHMS Calorimeter (Preshower+Shower)
Assembling and installation of the SHMS calorimeter: completed on 12 December 2014
40
YerPhI contribution in 12 GeV upgrade: Aerogel SHMS Aerogel detector
Type of
Particle
Pth in
n=1.030
Pth in
n=1.015
Pth in
n=1.010
Pth in
n=1.006
μ 0.428 0.608 0.746 0.963
π 0.565 0.803 0.984 1.272
K 2.000 2.840 3.482 4.500
P 3.802 5.397 6.618 8.552
41
YerPhI group activities in Hall C At 6 GeV energy era:
Design and construction lead-glass electromagnetic calorimeters for SOS and HMS
spectrometers. In1994, they were recognized as the first operational detectors at Jlab.
Design and construction threshold aerogel Cherenkov detector for HMS which
played key role in a series of +/-, K+/- production experiments since 2003.
Participation in installation, data taking and analysis in more than ~50 experiments
Proposed and carried out first semi-inclusive charged pion electroproduction
experiment E-00-108, “Duality in Meson Electroproduction”.
At 12 GeV energy era:
Design and construction electromagnetic calorimeter for SHMS spectrometer
Design and construction aerogel detectors for SHMS (in collaboration with CUA)
Proposed (in collaboration with Jlab & CUA) experiments
- E12-06-104, “Measurement of the Ratio R=σL/σT in Semi-Inclusive DIS”
- E12-09-017, “Transverse Momentum Dependence of Semi-Inclusive π-production”
- E12-13-007, “Measurement of Semi-Inclusive π0 Production“. Required
construction of the Neutral Particle Spectrometer (NPS).
YerPhI group will played leading role in development and construction of NPS.
42
YerPhI group members in Hall C
1. Tsolak Amatuni
2. Ashot Gasparian
3. Ruben Badalyan
4. Grigor Kazaryan
5. Vardan Tadevosyan
6. Samvel Stepanyan
7. Hamlet Mkrtchyan
8. Razmik Asaturyan
9. Arthur Mkrtchyan
10. Arshak Asaturyan
11. Simon Zhamkochyan
Thanks for Your Attention !
43
44 Slide from Hugh Montgomery.
Hall A meeting, December 2014
45 Slide from Hugh Montgomery.
Hall A meeting, December 2014
46
Aerogel Detector in the SHMS
The Aerogel detector is situated between heavy gas (C4F8O) Čerenkov detector and S2
Hodoscopes of the SHMS detector stack
A dedicated kaon PID detector
With dimensions 113x103x28 cm3, covers SHMS acceptance
2 detectors possible
Consists of a diffusion box with 14 PMTs (plus optional 6 on top) and 4 replaceable
trays with Aerogel of different indexes: 1.03, 1.02, 1.015, 1.011
Detector Hut Aerogel Detector
47
The NPS is envisioned as a facility in Hall C, utilizing the well-understood HMS
and the infrastructure of the new SHMS, to allow for precision (coincidence) cross
section measurements of neutral particles (,0).
NPS cantilevered off SHMS platform NPS on SHMS platform
Detector Detector
Magnet
Magnet
NPS angle range: 25 – 60 degrees NPS angle range: 5.5 – 30 degrees
The Neutral-Particle Spectrometer (NPS)
Currently 5 experiments are approved by the JLab PAC (three with A-
rating), which require the availability of the NPS
Ideas exist for new scientific directions, e.g., using a polarized
(transverse) target and LD2
The NPS design is flexible and could also be used in Hall A
48 new and currently at development stage, IR curing (λ>900 nm)
NPS Prototype Design
• Components of the NPS prototype
• NPS prototype is being constructed to optimize technical aspects of the calorimeter before finalizing the design of the NPS
o Crystal matrix: 3×3 PbWO4 (SICCAS, 2014), each 2.×2.×20. cm3 in a copper frame
o Light Monitoring System based on Blue Light source >450 nm (matrix of LEDs)
o Curing of the crystals will test two approaches:
standard, based on a blue light source (λ~460 nm)
49
E12-09-002:Precise Measurement of π+ ∕ π- Ratios in SIDIS
• In parton distribution functions, it is routinely assumed that charge symmetry is valid.
• Charge symmetry implies the invariance of up and
down quarks in proton and neutrons, i.e.
up(x, Q2) = dn(x, Q2)
dp(x, Q2) = un(x, Q2)
• Charge symmetry in the valence quark distribution
has never been tested with precision. The most
precise estimations (by NMC) gives the upper limit
of 9% for charge symmetry violation effects.
Goal: To measure precision ratios of charged pion electroproduction
in SIDIS from Deuterium. Data will be used to test the validity of the
charge symmetry (CS) in the valence quark distributions.
At large x, neglecting the sea quark contribution: The upper and lower limit of CSV contribution
(Calculations based on MRST
parameterization)
),(
),(),(
zxY
zxYzxR
y
)()(2
zDxqeYiii
)(3
)(4)(
vvdu
udxCR
)()()(
)()()(
xdxuxu
xuxdxd
np
np
Experiment will measure the ratio of the π+ and π-
yields on deuterium for different x & z:
where
x-dependence of R at fixed z
is a sensitive probe of CSV
where
50
E12-09-011:Studies of the L-T Separated Kaon Electroproduction
• The p{e,e’K+ )Λ and p(e,e’K+)Σ reactions are important tool in our study of hadron structure.
• Separated p{e,e’K+)Λ, Σ0 cross sections allow
investigations of the transition from hadronic to par
tonic degrees of freedom in exclusive processes.
• Practically no any data above the resonance region.
The Q2 dependence of p{e,e’K+)Λ, Σ0 cross
section is the main interests of proposal.
dtd
d
dEdd
d
v
Kee
25
2coscos)1(22
2
dt
d
dt
d
dt
d
dt
d
dtd
dTTLTLT
• The existing data have large uncertainties, they suggest significant contribution of σT at Q
2~2 GeV2.
• The Reggie model suggest strong Q2 and W dependence of the σL/σT.