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Journal ArticleDOI

Studies on the Magnetic Center of the Mu2e Solenoid System

01 Jan 2014-IEEE Transactions on Applied Superconductivity (IEEE)-Vol. 24, Iss: 3, pp 1-4

AbstractThe definition of the magnetic center in the Mu2e solenoid system is not trivial given the S-shaped nature of the transport solenoid. Moreover, due to the fringe field of the larger bore adjacent magnets-production solenoid and the detector solenoid-the magnetic center does not coincide with the geometric center of the system. The reference magnetic center can be obtained by tracking a low-momentum charged particle through the whole system. This paper will discuss this method and will evaluate the deviations from the nominal magnetic center given the tolerances in the manufacturing and the alignment of the coils. Methods for the correction of the magnetic center will also be presented.

Topics: Solenoid (65%), Magnet (53%), Mu2e (51%)

Summary (1 min read)

II. MAGNETIC CENTER VERSUS GEOMETRIC CENTER

  • In general, straight solenoids have a well-defined magnetic axis.
  • Fig. 2 shows, schematically, the difference between the geometric center of the coils and the magnetic center.
  • Fig 3 shows the track of three different momentum particles through the magnetic system with respect to its geometric center.
  • Figure 4 shows the transverse cross section of the muon beam at the entrance of the third collimator (located at the last TS straight section).
  • Average and standard deviations are calculated at each point of the track.

IV. VERTICAL ALIGNMENT

  • The first curve in TS will drift the beam vertically; the drift is proportional to momentum of the particles.
  • Given the orientation of the field, negative particles drift upward and positive particles drift downward.
  • After the first curve, the beam goes through an asymmetric collimator (Fig 7 ).
  • The vertical alignment of the magnetic center is especially critical in the middle collimator region.
  • Normally, 105 MeV electrons coming from the production target are intercepted by the middle collimator.

B. Correction coils

  • Another method that was investigated was the use of correction coils.
  • The interesting thing about the correction coils for solenoid systems is that for a vertical beam displacement, one has to apply a vertical field, unlike beam in accelerator where a vertical field displaces the beam horizontally.
  • This displacement, again, is independent of the particle momentum.
  • The quench 4OrDB-05 protection will be also an issue.

C. Trim power supplies

  • Another option to tune the beam position is the use of trim power supplies (TPS).
  • In order to allow 105 MeV electrons to be displaced upwards, one must reduce the current on the coils.
  • The mechanical tolerances were fixed at 0.2 o in order to keep the RMS displacements lower than 3 mm.
  • The magnetic center can be measured in the same way as presented here.
  • In the event that corrections are needed, a controlled misalignment of TSu can provide the necessary vertical displacement.

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4OrDB-05
1
Studies on the Magnetic Center of the Mu2e Solenoid
System
M. L. Lopes, G. Ambrosio, M. Buehler, R. Coleman, D. Evbota,
V. Khalatian, M. Lamm, G. Moretti, T. Page, M. Tartaglia, Fermilab,
J. Miller, Boston University
AbstractThe definition of the magnetic center in the Mu2e
solenoid system is not trivial given the S-shaped nature of the
transport solenoid (TS). Moreover, due to the fringe field of the
larger bore adjacent magnets production solenoid (PS) and the
detector Solenoid (DS) the magnetic center does not coincide
with the geometric center of the system. The reference magnetic
center can be obtained by tracking a low momentum charged
particle through the whole system. This paper will discuss this
method and will evaluate the deviations from the nominal
magnetic center given the tolerances in the manufacturing and
the alignment of the coils. Methods for the correction of the
magnetic center will also be presented.
Index TermsSolenoid, Superconducting Magnets, Beam
Transport
I. INTRODUCTION
HE Mu2e experiment [1] proposes to measure the ratio of
the rate of the neutrino-less, coherent conversion of muons
into electrons in the field of a nucleus, relative to the rate of
ordinary muon capture on the nucleus. The conversion process
is an example of charged lepton flavor violation, a process that
has never been observed experimentally. The conversion of a
muon to an electron in the field of a nucleus occurs
coherently, resulting in a monoenergetic electron (105 MeV)
near the muon rest energy that recoils off of the nucleus in a
two-body interaction. At the proposed Mu2e sensitivity there
are a number of processes that can mimic a muon-to-electron
conversion signal. Controlling these potential backgrounds
drives the overall design of Mu2e. The overview of the Mu2e
experiment can be seen in Fig 1. It is primarily formed by
three large solenoid systems: the production solenoid (PS) [2]
the transport solenoid (TS) [3] and the detector solenoid (DS)
[4]. The muon beam is created by an 8 GeV, pulsed beam of
protons striking a production target.
Fig. 1. The Mu2e experiment overview
Manuscript received July 16, 2013. Work supported in part by FRA under
DOE Contract DE-AC02-07CH11359.
M. L. Lopes - Fermi National Accelerator Laboratory, Batavia, IL 60510
USA (mllopes@fnal.gov).
The negative magnetic field gradient in the PS creates a
mirror effect on the charged particles produced after the
collision, pushing the beam downstream. This beam is then
transported by the TS. The three collimators in TS provide
charge and momentum selection. In the DS, the muon beam is
stopped in the stopping target and the 105 MeV electrons from
the conversion are detected in the tracker.
The magnetic system is formed by 3 coils for PS, 52 Coils
for TS and 11 coils for DS. Each subsystem is in a separate
cryostat module. TS is divided into two cryostats (named TSu
and TSd).
II. M
AGNETIC CENTER VERSUS GEOMETRIC CENTER
In general, straight solenoids have a well-defined magnetic
axis. The magnetic axis is important because it determines the
beam center. Very often, because of limitation in the
construction, the magnetic axis does not coincide with the
geometric center of a straight solenoid. In general, magnetic
measurements should be carried out to relate them.
The magnetic center of the Mu2e solenoid system cannot be
easily determined, given the S-shape nature of the TS. Fig. 2
shows, schematically, the difference between the geometric
center of the coils and the magnetic center. Just like in a
straight solenoid, the beam follows the magnetic center of the
TS. The knowledge of that is crucial because the experiment
relies on collimators to make both charge and momentum
selection. If the beam is off-set with respect to a collimator,
that may impact the muon transmission through the channel.
-5000 0 5000 10000 15000
-5000
-4000
-3000
-2000
-1000
0
1000
2000
3000
4000
5000
Z [mm]
X [mm]
Centroid
Nominal Traject ory
Fig. 2. Schematics of the geometric center (dashed line) vs. the magnetic
center (solid line). The differences between the two were exaggerated for
clarity.
T
FERMILAB-CONF-13-263-TD
Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy

4OrDB-05
2
III. LOW-MOMENTUM PARTICLE TECHNIQUE
The magnetic center can be determined by tracking a low-
momentum charged particle (LMCP). The vertical drift is
relatively small; therefore it stays close to the geometric
center. Fig 3 shows the track of three different momentum
particles through the magnetic system with respect to its
geometric center.
-8000 -6000 -4000 -2000 0 2000 4000
6000 8000
-30
-20
-10
0
10
20
30
Nominal tracks with respect to the centroid of the coils
1 MeV e-
Horizontal
Vertical
-8000 -6000 -4000 -2000 0
2000 4000
6000 8000
-50
0
50
100
150
Displacement (mm)
25 MeV/c
µ
-
-8000 -6000 -4000 -2000
0 2000 4000 6000 8000
-50
0
50
100
150
s (mm)
50 MeV/c
µ
-
Fig. 3. Track of particles through the TS. Top: 1MeV e
-
, Middle: 25 MeV/c
µ
-
, Bottom: 50 MeV/c µ
-
.
Figure 4 shows the transverse cross section of the muon
beam (simulated) at the entrance of the third collimator
(located at the last TS straight section). In red is the result
before corrections in the toroidal magnetic system. As can be
seen, the center of the beam is displaced by 100 mm. Taking
into consideration that the collimator radius is 150 mm, a
significant portion of the beam will be lost. This problem is
caused by the fringe field of the adjacent solenoids (PS and
DS) extending into the curves. This can be corrected by
applying an extra yaw angle (~1 degree) on the coils that
compose the curves (Fig 5). In blue is the result after the
magnetic design was corrected.
This simulation, using G4Beamline [5], takes a relatively
long time (~1 h). The tracking of a single MeV e
-
is very fast
(<1 min) and was sufficient to correct the beam position.
Fig. 4. The transverse cross section of the muon beam (simulated) at the
entrance of the third collimator. Red: before the correction; blue: after the
correction.
This technique can be used to study the geometrical
tolerances of the magnetic system. Simulations of three
different energy particles going through the transport solenoid
were done. In each simulation a different random error was
applied to each coil. The difference between the track in the
perturbed state and at the nominal position is computed. The
process is repeated 100 times for statistics. Average and
standard deviations are calculated at each point of the track.
Fig. 5. Mu2e solenoid system. The coils in blue represent the ones with extra
yaw of ~1
o
(the picture shows an exaggerated effect for clarity).
Figures 6 shows the standard deviation as function of the
positions, when a random error of up to 5 mrad is applied to
the pitch angle of each coil. The pitch angle only affects the
vertical position of the magnetic center. Likewise, yaw errors
only affect the horizontal displacement.
As can be seen, the relative change of the beam position is
independent of the particle momentum. Therefore, the
standard deviation of a LMCP can be used as an indication of
the displacement of the magnetic center. The advantage is that
LMCPs have a very small pitch compared to the general
dimensions of the magnets and the strength of the TS
magnetic fields (from 2.5 to 2 T). Hence the errors associated
with the calculation of the magnetic center with respect to the
geometric center are minimized.
-8000
-6000
-4000 -2000
0
2000
4000 6000
8000
-10
-5
0
5
10
Displacement with respect to the nominal track
1 MeV e-
Vertical
-8000 -6000
-4000
-2000 0
2000
4000 6000
8000
-10
-5
0
5
10
Displacement (mm)
25 MeV/c
µ
-
-8000 -6000
-4000
-2000 0
2000 4000
6000
8000
-10
-5
0
5
10
s (mm)
50 MeV/c
µ
-
Fig. 6. Standard deviation as function of the trajectory of the perturbed coils
system when random errors of up to 5 mrad are present.
This technique was applied to study the sensitivity of three
translational errors of the coils (X, Y and Z) and the two

4OrDB-05
3
rotation angles (yaw and pitch). The errors associated with the
rotations are more critical for the displacement of the magnetic
center. The mechanical specifications for the coils placement
were limited to be smaller than 0.2
o
. In that case the maximum
RMS deviation is limited to ~3 mm.
IV. V
ERTICAL ALIGNMENT
As mentioned before, one of the functions of TS is
momentum and charge selection. The first curve in TS will
drift the beam vertically; the drift is proportional to
momentum of the particles. Given the orientation of the field,
negative particles drift upward and positive particles drift
downward. After the first curve, the beam goes through an
asymmetric collimator (Fig 7). The second curve of TS brings
the beam back to the center.
Fig. 7. Asymmetric collimator located in between the two curves.
The vertical alignment of the magnetic center is especially
critical in the middle collimator region. Normally, 105 MeV
electrons coming from the production target are intercepted by
the middle collimator. Studies have shown that misalignments
may allow these electrons to go through the collimator and
make their way to the detector, mimicking the signal from the
conversion. In that case, the beam needs to be displaced
upwards so that the 105 MeV electrons hit the upper region of
the collimator.
A. Gravity supports
In the previous section the track of a LMCP was used to
determine the mechanical tolerances due to random errors on
the positioning of the coils. The same technique can be used to
study the mechanical tolerances that must be achieved by each
TS cryostat.
Figure 8 shows the TSu cold mass with its radial, axial and
gravity supports. The present design has three pairs of gravity
supports (TS1, TS2 and TS3). The gravity supports can be
used to intentionally misalign the coils, that is, introduce a
systematic pitch angle error to affect the vertical displacement
of the magnetic center on the middle collimator. Table I
summarizes the results of the shift in vertical magnetic center
as function of different gravity supports misalignments.
TABLE I
V
ERTICAL MAGNETIC CENTER DISPLACEMENT AS FUNCTION OF THE GRAVITY
SUPPORTS MISALIGNMENT
. UNITS ARE mm.
TS3
0
10
20
30
TS1
0
0.0
6.4
12.7
19.0
10
-4.0
2.3
8.7
15.0
20
-8.0
-1.6
4.7
11.0
30
-11.9
-5.6
0.7
7.0
The maximum displacement of 19 mm is achieved when the
TS3 gravity support is lifted (or lowered) by 30 mm and the
TS1 is left at the nominal elevation. The disadvantage of this
method is that solenoids naturally align their axis. Therefore a
centering force of -68 kN will appear. This amount can be
handled by the gravity supports (in either direction).
Fig. 8. TSu cold mass with the supports.
B. Correction coils
Another method that was investigated was the use of
correction coils. A dipole winding could be placed on top of
the first straight section (Figure 9). The interesting thing about
the correction coils for solenoid systems is that for a vertical
beam displacement, one has to apply a vertical field, unlike
beam in accelerator where a vertical field displaces the beam
horizontally. A 0.1 T-m integrated field from the correction
coil will result in around 40 mm beam displacement (Figure
10). This displacement, again, is independent of the particle
momentum.
Fig. 9. A vertical correction coil model.
The disadvantage of a correction coil is the considerable
complication in the design of the magnetic system. The
needed integrated field is relatively high and its location (in
the PS fringe field) would subject the coils to high forces. The
mechanical support would be complicated. The quench

4OrDB-05
4
protection will be also an issue. All result in a significant
increment in the overall cost of the magnet.
C. Trim power supplies
Another option to tune the beam position is the use of trim
power supplies (TPS). Those devices typically allow changes
of a few percent of the main current. Figure 11 shows,
schematically, the coils where a TPS is employed.
In order to allow 105 MeV electrons to be displaced
upwards, one must reduce the current on the coils. A reduction
of 10% of the current results in these electrons moving around
20 mm up. An interesting fact is that this kind of modification
is momentum-dependent; the LMCP technique does not apply
in this particular case. 105 MeV electrons were tracked
instead. Table II summarizes the results of the horizontal and
vertical displacements (with respect to the coils in nominal
conditions) of electrons with different energies.
Fig. 10. Vertical beam displacement using a correction coil located in the first
straight section.
Fig. 11. Mu2e solenoid system. The coils in blue represent the ones powered
with trim power supplies.
TABLE
II
V
ERTICAL AND HORIZONTAL DISPLACEMENT USING TRIM POWER SUPPLIES.
UNITS ARE mm.
105 MeV
1 MeV
Vertical
19.0
-1.4
Horizontal
-1.4
3.1
V. CONCLUSION
Tracking studies have shown that the beam follows the
magnetic center. A technique to determine the magnetic center
of the Mu2e solenoid system was discussed. The technique is
useful to predict displacements and indicate corrections to the
magnetic design in a reliable and fast way. The technique was
also used to estimate the mechanical tolerances of the support
structures. The most restrictive tolerance has to do with the
angles of the coils (yaw and pitch). The mechanical tolerances
were fixed at 0.2
o
in order to keep the RMS displacements
lower than 3 mm.
The magnetic center can be measured in the same way as
presented here. The use of a beta source or even a cathode
installed in the same location as the production target in PS is
planned to be used [6]. The position could be measured with a
detector in between TSu and TSd. In the event that corrections
are needed, a controlled misalignment of TSu can provide the
necessary vertical displacement. In that case a vertical
centering force will push the magnet back to the center. The
supports are design to withstand those additional forces.
During the commissioning of the experiment, a trim power
supply (connected to the majority of the coils that compose the
first curve) can be used on-the-fly for calibration purposes.
R
EFERENCES
[1] Mu2e Collaboration, "Mu2e Conceptual Design Report",
arXiv:1211.7019, http://arxiv.org/abs/1211.7019
[2] V. V. Kashikhin et al., “Conceptual Design of the Mu2e Production
Solenoid Cold Mass,” Advances in Cryogenic Engineering, AIP Conf.
Proc., 1434, 893-900 (2012).
[3] G. Ambrosio et al. "Challenges and Design of the Transport Solenoid
for the Mu2e experiment"- this conference;
[4] S. Feher et al. "Reference Design of the Mu2e Detector Solenoid" -
this conference.
[5] J. Miller, R. Coleman Reference.
[6] M. Buehler et al. "Mu2e Magnetic Measurements", this conference
(3PoAJ-12)
Citations
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Journal ArticleDOI
Abstract: The Fermilab Mu2e experiment has been developed to search for evidence of charged lepton flavor violation through the direct conversion of muons into electrons. The transport solenoid is an s-shaped magnet that guides the muons from the source to the stopping target. It consists of 52 superconducting coils arranged in 27 coil modules. A full-size prototype coil module, with all the features of a typical module of the full assembly, was successfully manufactured by a collaboration between INFN-Genoa and Fermilab. The prototype contains two coils that can be powered independently. To validate the design, the magnet went through an extensive test campaign. Warm tests included magnetic measurements with a vibrating stretched wire and electrical and dimensional checks. The cold performance was evaluated by a series of power tests and temperature dependence and minimum quench energy studies.

23 citations


Cites background from "Studies on the Magnetic Center of t..."

  • ...For the transport solenoid, the angular coil orientation during operation—cold and powered—is very important in order to obtain the proper magnetic alignment [7]....

    [...]


Journal ArticleDOI
Abstract: The Fermilab Mu2e experiment seeks to measure the rare process of direct muon to electron conversion in the field of a nucleus. The magnet system for this experiment is made of three warm-bore solenoids: the Production Solenoid (PS), the Transport Solenoid (TS), and the Detector Solenoid (DS). The TS is an “S-shaped” solenoid set between the other bigger solenoids. The Transport Solenoid has a warm-bore aperture of 0.5 m and field between 2.5 and 2.0 T. The PS and DS have, respectively warm-bore aperture of 1.5 m and 1.9 m, and peak field of 4.6 T and 2 T. In order to meet the field specifications, the TS starts inside the PS and ends inside the DS. The strong coupling with the adjacent solenoids poses several challenges to the design and operation of the Transport Solenoid. The coil layout has to compensate for the fringe field of the adjacent solenoids. The quench protection system should handle all possible quench and failure scenarios in all three solenoids. The support system has to be able to withstand very different forces depending on the powering status of the adjacent solenoids. In this paper, the conceptual design of the Transport Solenoid is presented and discussed focusing on these coupling issues and the proposed solutions.

15 citations


Cites background from "Studies on the Magnetic Center of t..."

  • ...A trim power supply for TS2 coils is under consideration for vertical correction before the TS3 collimator [9]....

    [...]

  • ...The fringe field causes the beam to have a horizontal offset that could reduce significantly the muon transmission [9]....

    [...]

  • ...An asymmetric collimator [9] placed in the second straight section (TS3) makes the charge and momentum selection....

    [...]

  • ...The results [9], [10] show that the magnetic design is very robust, meeting all requirements even when significant coil misalignments are present....

    [...]


Journal ArticleDOI
Abstract: The muon-to-electron conversion experiment at Fermilab is designed to explore charged lepton flavor violation. It is composed of three large superconducting solenoids, namely, the production solenoid, the transport solenoid, and the detector solenoid. Each subsystem has a set of field requirements. Tolerance sensitivity studies of the magnet system were performed with the objective of demonstrating that the present magnet design meets all the field requirements. Systematic and random errors were considered on the position and alignment of the coils. The study helps to identify the critical sources of errors and which are translated to coil manufacturing and mechanical support tolerances.

9 citations


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  • ...The mechanical tolerances for the TS coils are given by other sources [6]....

    [...]


DOI
01 Jul 2014
Abstract: SolCalc is a software suite that computes and displays magnetic fields generated by a three dimensional (3D) solenoid system. Examples of such systems are the Mu2e magnet system and Helical Solenoids for muon cooling systems. SolCalc was originally coded in Matlab, and later upgraded to a compiled version (called MEX) to improve solving speed. Matlab was chosen because its graphical capabilities represent an attractive feature over other computer languages. Solenoid geometries can be created using any text editor or spread sheets and can be displayed dynamically in 3D. Fields are computed from any given list of coordinates. The field distribution on the surfaces of the coils can be displayed as well. SolCalc was benchmarked against a well-known commercial software for speed and accuracy and the results compared favorably.

3 citations


Cites background from "Studies on the Magnetic Center of t..."

  • ...Figure 2 shows a plot of the absolute field distribution for the Mu2e Transport Solenoids (TS) [8-11]....

    [...]


Journal ArticleDOI
Thomas Strauss1, Sandor Feher1, Horst W. Friedsam1, M.J. Lamm1, Thomas H. Nicol1, T. Page1 
Abstract: The Mu2e experiment at Fermilab is designed to search for charged-lepton flavor violation by looking for muon to electron conversions in the field of the nucleus. The concept of the experiment is to generate a low momentum muon beam, stopping the muons in a target and measuring the momentum of the outgoing electrons. The implementation of this approach utilizes a complex magnetic field composed of graded solenoidal and toroidal fields. Monitoring coil movements of the solenoids during cool down and magnet excitation and cool down is needed. A novel design of a Cold Mass Position Monitor System (CMPS) that will be implemented for the Mu2e experiment has been developed and a prototype CMPS has been built and tested. This paper describes the Mu2e Solenoid System CMPS including the description of the calibration, mounting effort and the CMPS DAQ.

2 citations


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  • ...The DS has the tightest constraints on knowing the magnetic field and solenoid coil positions [11], [12]....

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References
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Proceedings ArticleDOI
25 Jun 2007
Abstract: G4beamline is a single-particle simulation program optimized for the design and evaluation of beam lines. It is based on the Geant4 toolkit, and can implement accurate and realistic simulations of particle transport in both EM fields and matter. This makes it particularly well suited for studies of muon collider and neutrino factory design concepts. G4beamline includes a rich repertoire of beamline elements and is intended to be used directly, without C++ programming, by accelerator physicists. The program has been enhanced to handle a large class of beamline and detector systems, and is available on Linux, Windows, and Macintosh platforms.

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  • ...The simulation using G4Beamline [5] takes a relatively long time (∼1 h)....

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Journal ArticleDOI
Abstract: The Fermilab Mu2e experiment seeks to measure the rare process of direct muon to electron conversion in the field of a nucleus. The magnet system for this experiment is made of three warm-bore solenoids: the Production Solenoid (PS), the Transport Solenoid (TS), and the Detector Solenoid (DS). The TS is an “S-shaped” solenoid set between the other bigger solenoids. The Transport Solenoid has a warm-bore aperture of 0.5 m and field between 2.5 and 2.0 T. The PS and DS have, respectively warm-bore aperture of 1.5 m and 1.9 m, and peak field of 4.6 T and 2 T. In order to meet the field specifications, the TS starts inside the PS and ends inside the DS. The strong coupling with the adjacent solenoids poses several challenges to the design and operation of the Transport Solenoid. The coil layout has to compensate for the fringe field of the adjacent solenoids. The quench protection system should handle all possible quench and failure scenarios in all three solenoids. The support system has to be able to withstand very different forces depending on the powering status of the adjacent solenoids. In this paper, the conceptual design of the Transport Solenoid is presented and discussed focusing on these coupling issues and the proposed solutions.

15 citations


"Studies on the Magnetic Center of t..." refers background in this paper

  • ...) they are not part of the TS present design [3]....

    [...]

  • ...It is primarily formed by three large solenoid systems: the Production Solenoid (PS) [2] the Transport Solenoid (TS) [3] and the Detector Solenoid (DS) [4]....

    [...]

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    [...]


Proceedings ArticleDOI
12 Jun 2012
Abstract: The Muon-to-Electron conversion experiment (Mu2e), under development at Fermilab, seeks to detect direct muon to electron conversion to provide evidence for a process violating muon and electron lepton number conservation that cannot be explained by the Standard Model of particle physics The required magnetic field is produced by a series of superconducting solenoids of various apertures and lengths This paper describes the conceptual design of the 5 T, 4 m long solenoid cold mass with 167 m bore with the emphasis on the magnetic, radiation and thermal analyses

12 citations


"Studies on the Magnetic Center of t..." refers background in this paper

  • ...It is primarily formed by three large solenoid systems: the Production Solenoid (PS) [2] the Transport Solenoid (TS) [3] and the Detector Solenoid (DS) [4]....

    [...]


Journal ArticleDOI
Abstract: The Mu2e experiment at Fermilab has been approved by the Department of Energy to proceed with the development of the preliminary design. Integral to the success of Mu2e is the superconducting solenoid system. One of the three major solenoids is the detector solenoid that houses the stopping target and the detectors. The goal of the detector solenoid team is to produce detailed design specifications that are sufficient for vendors to produce the final design drawings, tooling and fabrication procedures and proceed to production. In this paper we summarize the reference design of the detector solenoid.

10 citations


"Studies on the Magnetic Center of t..." refers background in this paper

  • ...It is primarily formed by three large solenoid systems: the Production Solenoid (PS) [2] the Transport Solenoid (TS) [3] and the Detector Solenoid (DS) [4]....

    [...]


DOI
01 Jul 2014
Abstract: The Mu2e experiment at Fermilab is designed to explore charged lepton flavor violation by searching for muon-to-electron conversion. The magnetic field generated by a system of solenoids is crucial for Mu2e and requires accurate characterization to detect any flaws and to produce a detailed field map. Stringent physics goals are driving magnetic field specifications for the Mu2e solenoids. A field mapper is being designed, which will produce detailed magnetic field maps. The uniform field region of the spectrometer volume requires the highest level of precision (1 Gauss per 1 Tesla). During commissioning, multiple magnetic field maps will be generated to verify proper alignment of all magnet coils, and to create the final magnetic field map. In order to design and build a precise field mapping system consisting of Hall and NRM probes, tolerances and precision for such a system need to be evaluated. In this paper we present a design for the Mu2e field mapping hardware, and discuss results from OPERA-3D simulations to specify parameters for Hall and NMR probes. We also present a fitting procedure for the analytical treatment of our expected magnetic measurements.

3 citations


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  • ...The use of a beta source or even a cathode installed in the same location as the production target in PS is planned to be used [6]....

    [...]


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Frequently Asked Questions (1)
Q1. What are the contributions mentioned in the paper "Studies on the magnetic center of the mu2e solenoid system" ?

The reference magnetic center can be obtained by tracking a low momentum charged particle through the whole system. This paper will discuss this method and will evaluate the deviations from the nominal magnetic center given the tolerances in the manufacturing and the alignment of the coils.