In 2007, at the Institute of Nuclear Physics (Novosibirsk), the construction of the VEPP-2000 electron-positron collider was completed. The first electron beam was injected into the accelerator ...structure with turned-off solenoids of the final focus. This mode was used to tune all subsystems of the facility and to train the vacuum chamber using synchrotron radiation at electron currents of up to 150 mA. The VEPP-2000 structure with small beta functions and partially turned-on solenoids was used for the first testing of the “round beams” scheme at an energy of 508 MeV. Beam-beam effects were studied in strong-weak and strong-strong modes. Measurements of the beam sizes in both cases showed a dependence corresponding to model predictions for round colliding beams. Using a modernized SND (spherical neutral detector), the first energy calibration of the VEPP-2000 collider was performed by measuring the excitation curve of the phimeson resonance; the phi-meson mass is known with high accuracy from previous experiments at VEEP-2M. In October 2009, a KMD-3 (cryogenic magnetic detector) was installed at the VEPP-2000 facility, and the physics program with both the SND and LMD-3 particle detectors was started in the energy range of 1–1.9 GeV. This first experimental season was completed in summer 2010 with precision energy calibration by resonant depolarization.
The process e+ e−→ K+ K−π0 has been studied in the center-of-mass energy range from 1.2 to 2 GeV using a 80.6 pb−1 data sample collected with the CMD-3 detector at the electron-positron collider ...VEPP-2000. Preliminary results of the cross-section measurement are presented.
The sensitivity of the VEPP-2000
e
+
e
−
collider in the search for the rare decay η →
e
+
e
−
has been studied. The inverse reaction
e
+
e
−
→ η is proposed for this search. We have analyzed a data ...sample with an integrated luminosity of 108 nb
−1
collected with the SND detector in the center-of-mass energy range 520–580 MeV and found no background events for the reaction
e
+
e
−
→ η in the decay mode η → π
0
π
0
π
0
. In the absence of background, a sensitivity to B(η →
e
+
e
−
) of 10
−6
can be reached during two weeks of VEPP-2000 operation. Such a sensitivity is higher than the current upper limit on B(η →
e
+
e
−
) by a factor of 2.3.
The process
e
+
e
−
→
K
+
K
−
π
0
has been studied in the center-of-mass energy range from 1.2 to 2 GeV using a 80.6 pb
−1
data sample collected with the CMD-3 detector at the electron-positron ...collider VEPP-2000. Preliminary results of the cross-section measurement are presented.
CMD-3 Overview Logashenko, Ivan B.; Ignatov, F.V.; Akhmetshin, R.R. ...
EPJ Web of Conferences,
2019, Letnik:
218
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The CMD-3 detector is installed at the VEPP-2000
e
+
e
−
collider at BINP (Novosibirsk, Russia). It is a general-purpose detector, equipped with a tracking system, two crystal (CSI and BGO) ...calorimeters, liquid Xe calorimeter, TOF and muon systems. The main goal of experiments at CMD-3 is a study of exclusive modes of
e
+
e
−
→
hadrons
at energies $ \sqrt s \le $ GeV. In particular, these results provide an important input for calculation of the hadronic contribution to the muon anomalous magnetic moment.
The first round of data taking was performed in 2011–2013, when about 60 1/pb were taken in the center-of-mass (c.m.) energy range from 0.32 to 2.0 GeV. Here we present a survey of results of data analysis.
Between 2013 and 2016 the collider and the detector were upgraded. The data taking resumed by the end of 2016. In the first run after the upgrade about 50 1/pb were collected at the energy range between 1.28 and 2.007 GeV. We discuss the upgrade and the first preliminary results from the new data.
Many different genetic alterations are observed in cancer cells. Individual cancer genes display point mutations such as base changes, insertions and deletions that initiate and promote cancer growth ...and spread. Somatic hypermutation is a powerful mechanism for generation of different mutations. It was shown previously that somatic hypermutability of proto-oncogenes can induce development of lymphomas.
We found an exceptionally high incidence of single-base mutations in the tumor suppressor genes RASSF1 and RBSP3 (CTDSPL) both located in 3p21.3 regions, LUCA and AP20 respectively. These regions contain clusters of tumor suppressor genes involved in multiple cancer types such as lung, kidney, breast, cervical, head and neck, nasopharyngeal, prostate and other carcinomas. Altogether in 144 sequenced RASSF1A clones (exons 1-2), 129 mutations were detected (mutation frequency, MF = 0.23 per 100 bp) and in 98 clones of exons 3-5 we found 146 mutations (MF = 0.29). In 85 sequenced RBSP3 clones, 89 mutations were found (MF = 0.10). The mutations were not cytidine-specific, as would be expected from alterations generated by AID/APOBEC family enzymes, and appeared de novo during cell proliferation. They diminished the ability of corresponding transgenes to suppress cell and tumor growth implying a loss of function. These high levels of somatic mutations were found both in cancer biopsies and cancer cell lines.
This is the first report of high frequencies of somatic mutations in RASSF1 and RBSP3 in different cancers suggesting it may underlay the mutator phenotype of cancer. Somatic hypermutations in tumor suppressor genes involved in major human malignancies offer a novel insight in cancer development, progression and spread.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
At the end of 2016 the SND detector resumed data taking at the upgraded VEPP-2000
e
+
e
−
collider. The analysis of data accumulated in 2010-2013 with an integrated lumonosity of 70 pb
−1
is ...continuing. Recent results on measurements of various hadronic cross sections are presented.
A survey of preliminary results of experiments with the SND detector at the VEPP-2000
e
+
e
−
collider in the energy range of
= 1000–2000 MeV MeV is presented. The cross sections for the processes
e
...+
e
−
→ π
0
π
0
γ
,
e
+
e
−
→
π
+
π
−
π
0
π
0
,
e
+
e
−
→
π
+
π
−
π
0
,
e
+
e
−
→
π
+
π
−
η
, and
e
+
e
−
→
were measured. The measured cross sections agree with the results of earlier measurements but have a higher precision. The cross section for the process
e
+
e
−
→
ηγ
in the energy range extending from 1.4 to 2 GeV was measured for the first time. The ratio
G
E
/
G
M
for the neutron was measured for the first time in the timelike region.
PDF
